Huberman Links Morning Light to Cortisol Regulation for Better Sleep

Huberman将晨间光照与皮质醇调节关联以改善睡眠 使光照、体温和咖啡因与人体自然昼夜节律同步，可最大程度优化夜间睡眠结构并提高白天清醒度。 本期节目提供了一个分层的综合框架，旨在通过顺应人体的自然昼夜节律来优化睡眠结构与白天警觉度。Huberman强调了全天的关键时间窗口，重点指出清晨接受日光照射、推迟咖啡因摄入，以及通过锻炼或冷热暴露刻意调节核心体温的重要性。此外，内容还详细介绍了一种由苏糖酸镁、芹菜素和茶氨酸组成的协同三联补充剂方案，并提供了诸如追踪“最低体温点”等具体行为策略，以有效应对时差反应和轮班倒带来的节律紊乱。 清晨皮质醇的释放对唤醒机体至关重要，醒后30至60分钟内注视强光能够锚定这一节律。 (0:21) 视交叉上核是昼夜节律的主时钟，它对晨光做出反应以发出清醒信号，并启动夜间入睡的倒计时。 (0:21) 由于具有更高的光子能量，自然阳光在触发皮质醇觉醒机制方面远比智能手机屏幕或室内照明更有效。 (3:44) 阴天和多云天气需要比晴天（5分钟）更长的户外光照时间（20至30分钟），以达到相同的生物追踪效果。 (3:44) 通过刻意的冷暴露或晨练可以加速晨间核心体温的回升并提高警觉度。 (8:04)

Andrew Huberman presents a physiological framework for optimizing sleep and daytime alertness, arguing that sleep quality is primarily governed by behavioral timing across light exposure, core body temperature, and nutrient intake. Anchoring Circadian Rhythms with Morning Sunlight and Temperature Huberman emphasizes that a restorative 24-hour cycle begins at waking, when the body naturally raises its core temperature and triggers a necessary cortisol surge. To time this cortisol peak correctly and initiate the biological countdown toward nighttime sleep, individuals should view outdoor sunlight within 30 to 60 minutes of waking. Specialized melanopsin cells in the eyes transmit this signal to the master clock in the suprachiasmatic nucleus. Recommended outdoor exposure durations vary based on cloud cover: 5 minutes on a clear day, roughly 10 minutes on overcast days, and 20 to 30 minutes on densely cloudy or rainy mornings. Window glass and smartphone screens lack the photon intensity required to stimulate this mechanism properly. Behavioral Modulation via Cold, Exercise, and Delayed Caffeine Core temperature and alertness can be accelerated through deliberate cold exposure or physical movement. Cold water immersion for 1 to 3 minutes triggers adrenaline release while activating the medial preoptic area to heat up the core. Morning exercise—such as walking, jogging, or jumping rope—further reinforces temperature elevation without shifting the circadian clock. For caffeine users, Huberman suggests delaying consumption until 90 to 120 minutes after waking to clear residual adenosine and avoid an afternoon energy crash. Afternoon Protocols and Sunset Light Inoculation (14:51) During the middle and later parts of the day, behavioral choices directly influence evening sleep readiness. Afternoon exercise can delay the circadian clock, pushing back the time an individual feels tired. Viewing low-solar-angle evening sunlight for 5 to 30 minutes establishes a reference point that signals approaching darkness and protects against the sleep-disrupting effects of artificial indoor light encountered later at night. If napping occurs, Huberman advises keeping it under 90 minutes. Caffeine intake should remain below 100 milligrams after 4:00 p.m., as late consumption disrupts deeper sleep architecture even in individuals who fall asleep without difficulty. Evening Cooling, Light Minimization, and Sleep Aids (20:23) Starting around 6:00 or 7:00 p.m., indoor environments should be dimmed, avoiding bright overhead lights between 10:00 p.m. and 4:00 a.m. to prevent the suppression of natural melatonin. Unlike morning cold exposure, evening protocols should promote core cooling: a 20- to 30-minute hot bath, shower, or sauna induces a compensatory drop in core body temperature by 1 to 3 degrees, as does lowering bedroom temperatures by at least 3 degrees. While alcohol and cannabis are commonly used as sleep aids, Huberman cautions that they degrade restorative sleep architecture. When behavioral adjustments are insufficient, a targeted supplement stack taken 30 to 60 minutes before bed—145 milligrams of magnesium threonate, 50 milligrams of apigenin, and 100 to 400 milligrams of theanine—serves as an alternative to commercial melatonin, which often contains supra-physiological doses. Using the Temperature Minimum to Shift Sleep Timing (30:18) Circadian adjustment relies heavily on the 'temperature minimum,' a biological marker occurring approximately two hours prior to an individual's habitual wake-up time. Light exposure, exercise, or caffeine within the 2 to 4 hours before this minimum causes a phase delay, shifting sleepiness and wakefulness later. Conversely, engaging in these stimuli immediately after the temperature minimum creates a phase advance, shifting the biological clock earlier. For mid-night waking due to caregiving or shift work, Huberman recommends using red light to preserve visibility while avoiding daytime cortisol disruptions. Huberman frames behavioral habits as the mandatory foundation of sleep optimization, prioritizing light and temperature control over supplements or pharmacological interventions, while cautioning that individual tolerances—such as gastrointestinal side effects from magnesium or vivid dreams from theanine—require personal protocol adjustments.

神经生物学家 Andrew Huberman 指出，优质睡眠并非仅由睡前准备决定，而是始于清晨醒来的那一刻，受光照、体温和行为时间的系统性调控。他主张通过分阶段管理全天生理信号，主动建立早晨皮质醇峰值并利用体温与光照节律，来优化深层睡眠架构与白天的专注力。 晨间光照与核心体温的主动激活 Huberman 强调，人体在醒来时自然会启动核心体温上升，并促使皮质醇释放；健康节律的关键在于让皮质醇峰值尽早出现，而非在午后或夜间持续偏高。为了将该峰值锚定在正确时间，醒后 30 至 60 分钟内接收明亮光照至关重要。视网膜上的内源感光黑视蛋白细胞对低太阳高度角的晨光最为敏感，可直接向位于上颚正上方的主生物钟（视交叉上核）传递信号，在激发日间清醒的同时启动当晚入睡的内部倒计时。根据环境光照强度，晴天建议户外接触 5 分钟，多云天需约 10 分钟，阴雨天则需延长至 20 至 30 分钟。透过车窗或窗户玻璃会导致有效光能被过滤，而普通室内灯光和手机屏幕在早晨缺乏触发该机制所需的光子能量。 除光照外，体温是加速清晨清醒度的关键杠杆。醒后进行 1 至 3 分钟的冷水浸泡（如冷水澡或冰浴）会诱发大量肾上腺素释放，并促使下丘脑内侧视前区作为体内温度调节器，代偿性地积极升高身体核心温度。此外，醒后立即进行轻度运动（如晨间散步、慢跑或跳绳）同样能迅速拉升核心体温并巩固生物钟节律。关于饮食与兴奋剂，Huberman 建议将咖啡因摄入推迟到醒后 90 至 120 分钟，以允许体内腺苷有效代谢，从而避免午后精力骤降；同时避免在缺乏高强度运动的情况下摄入过大体积的早餐，以防血液转向消化系统引发昏睡感。 午后行为管理与黄昏光线防护 (14:51) 从上午延续至傍晚的第二关键阶段决定了夜间睡眠能否顺利启动。在此期间，Huberman 建议将下午 4:00 之后的咖啡因摄入量严格限制在 100 毫克以下；即使部分人群在傍晚饮用咖啡后仍能轻易入睡，同行评审研究表明这依然会破坏深层恢复性睡眠架构。对于习惯午睡的人群，午睡时长应控制在 90 分钟以内，或者采用非睡眠深度放松（NSDR），以防干扰夜间主睡眠块，同时不应强迫无午睡习惯者改变作息。 运动与光照在午后的运用同样深远影响节律走向。下午或傍晚进行的高强度剧烈运动会使核心体温升高，进而使昼夜节律发生相位延迟（推迟困意产生的时间），而醒后 0 至 4 小时内的运动则几乎不改变节律。此外，在日落前接触 5 至 30 分钟低太阳高度角的阳光至关重要。夕阳中的特定黄光、蓝光和橙光信号能向生物钟确认夜幕即将来临，并形成神经保护屏障，抵御夜间可能接触到的人工强光对昼夜节律的扰动。 夜间环境降温与人造光抑制 (20:23) 晚间大约 6:00 或 7:00 开始进入第三关键阶段，核心原则是彻底减少任何颜色的强人造光照射。Huberman 指出人类视网膜与大脑存在光敏不对称性：清晨微弱的人造光不足以唤醒生物钟，但夜晚哪怕少量的光线（尤其是晚 10:00 至凌晨 4:00 之间的头顶人工强光）就会彻底抑制内源性褪黑素的分泌，严重损害睡眠质量。若夜间因哺乳、工作等突发原因醒来，使用红光照明是唯一既能看清环境又不会破坏正常皮质醇节律的替代方案。 在温度调节方面，夜晚的逻辑与早晨完全相反。睡前进行 20 至 30 分钟的热水澡、泡澡或桑拿，会在离开热源后诱发体表散热，使核心体温代偿性下降 1 至 3 度，从而显著加速入眠。同时，睡眠环境本身应降温至少 3 度，偏冷的卧室配合被褥符合人体入睡生理，便于通过伸出四肢进行微调散热。对于酒精、THC 和 CBD，Huberman 明确指出虽然它们常被用作镇静剂以加速入眠，但从生物学角度来看，它们会严重割裂正常的睡眠阶段，剥夺具有修复性的深层休息。 阶梯式助眠与补充剂风险权衡 (25:01) Huberman 提出了严格的睡眠干预层级：首先必须建立行为习惯，其次是调整营养，之后才是针对性补充剂，最后是处方药物。对于行为习惯良好但仍需助眠支持的人群，他在睡前 30 至 60 分钟推荐的三联补充剂组合包括：145 毫克苏糖酸镁（约 5% 人群可能出现肠胃不适或腹泻，应停用）、50 毫克芹菜素，以及 100 至 400 毫克茶氨酸。但他提醒，茶氨酸可能引发部分人产生极度逼真或焦虑的梦境导致夜醒，此类人群需将其从组合中剔除。 相比之下，Huberman 强烈建议避免将非处方褪黑素作为日常补充剂。市售褪黑素产品通常含有远超生理剂量的浓度，由于褪黑素是一种直接影响睾酮、雌激素和儿童青春期发育的强效内源激素，长期高剂量摄入可能扰乱内分泌系统，因此仅宜偶尔用于倒时差。此外，保持周末作息与工作日一致至关重要；周末补觉不应超过正常起床时间 1 小时，否则会引发类似跨时区旅行的生物钟紊乱。 最低体温点与昼夜节律定向调校 (30:18) 为了精确掌控入睡与清醒时间（如应对时差或轮班工作），Huberman 引入了“最低体温点”这一关键概念。它并非一个温度数值，而是指 24 小时周期内核心体温降至最低的时间点，通常发生在个人常规醒来时间前约 2 小时（例如固定早晨 7:00 醒来的人，其最低体温点约在凌晨 5:00）。 利用该时间点可实现生物钟的双向调节：若在最低体温点之前的 2 至 4 小时内接触强光、摄入咖啡因或运动，会诱发“相位延迟”，使下一次就寝和醒来的节律整体推迟；相反，若在最低体温点刚过后的清晨进行光照、运动或进食，则会产生“相位提前”，促使身体在次日更早感到困倦并提前醒来。理解这套生物学规则，便能在跨时区出行或倒班前一至两天，主动通过光照和行为操纵节律，有效规避时差带来的生理混乱。 Huberman 总结认为，睡眠是心理健康、身体机能与日常表现的基石。上述睡眠工具集高度依赖行为层面的规律性，但现实生活中的轮班工作、育儿中断以及个体对特定补充剂的不良耐受反应，表明该协议需要根据个人实际情况灵活调整，且任何补充剂方案在实施前均应咨询执业医师。

Andrew Huberman: it takes far too long [14:51] Andrew Huberman: I love naps. I've always loved naps [20:23] Andrew Huberman: absolutely quash any melatonin that happens to be circulating in your brain and body. [22:06] Andrew Huberman: I'm not here to tell you what to do or not to do. I'm certainly not the substance police. [29:37] Andrew Huberman: your body doesn't know the difference between flying to a new time zone and getting woken up in the middle of the night. [33:33] Andrew Huberman: sleep is the absolute foundation of your mental health, your physical health, and your performance in all endeavors.

[0:00] Welcome to Hubberman Lab Essentials, [0:01] [music] where we revisit past episodes [0:04] for the most potent and actionable [0:06] science-based tools for mental health, [0:08] physical health, and performance. [0:11] I'm Andrew Huberman, and I'm a professor [0:13] of neurobiology and opthalmology at [0:16] Stanford School of Medicine. Today, [0:18] we're talking all about sleep and how to [0:20] optimize your sleep. Let's consider what [0:22] the perfect 24-hour cycle would look [0:26] like. Regardless of when you wake up in [0:28] the morning, one of the first things [0:30] that happens is that your body [0:31] temperature is increasing. And that's [0:33] just going to happen naturally. That [0:35] increase in body temperature in turn [0:38] causes an increase in the release of a [0:40] hormone called cortisol. Cortisol is [0:42] often con demonized and considered this [0:44] bad thing. And indeed, you don't want [0:46] cortisol to be chronically or [0:48] consistently elevated throughout the day [0:49] or night. But you do want cortisol to [0:52] reach its peak early in the day, right [0:54] about the time you wake up. One way that [0:57] you can ensure that that cortisol peak [0:59] occurs early in the day, right about the [1:01] time that you wake up, is to view bright [1:04] light, ideally from sunlight, within the [1:06] first 30 to 60 minutes after waking. The [1:09] reason for that is very simple. You want [1:12] to trigger that cortisol increase to [1:14] occur very early in your day, and you [1:17] don't want that cortisol peak to happen [1:19] later, which is what will happen if you [1:21] wait to get outside and see sunlight. [1:23] The reason for this is that you have a [1:26] set of neurons, nerve cells in your eye. [1:28] They're called intrinsically [1:29] photosensitive melanopsin cells, but you [1:31] do not need to know that name. Those [1:32] neurons respond best to bright light and [1:35] especially right after waking early in [1:37] the day. They are best able to signal to [1:40] a set of neurons that reside over the [1:42] roof of your mouth called the super kisa [1:44] nucleus which is a cluster of neurons [1:46] that then sends a huge number of other [1:48] signals electrical and chemical out to [1:50] your entire body that triggers that [1:52] cortisol increase provides a wakeup [1:54] signal for your brain and body and sets [1:56] in motion a timer for you to fall asleep [1:58] later that night. Here's what you do, or [2:00] at least here's what I do. I wake up in [2:01] the morning and I want to reach for my [2:03] phone. But I know that even if I were to [2:06] crank up the brightness on that phone [2:07] screen, it's not bright enough to [2:09] trigger that cortisol spike and for me [2:12] to be at my most alert and focused [2:15] throughout the day and to optimize my [2:16] sleep at night. So, what I do is I get [2:18] out of bed and I go outside and if it's [2:22] a bright clear day and the sun is low in [2:25] the sky or the sun is, you know, [2:27] starting to get overhead, what we call [2:28] low solar angle, then I know I'm getting [2:31] outside at the right time. Especially on [2:33] cloudy days, you want to get outside and [2:35] get as much light energy or photons in [2:37] your eyes. But let's say it's a very [2:39] clear day and I can see where the sun [2:41] is. I do not need to stare directly into [2:44] the sun. So, the way to get this [2:46] sunlight viewing early in the day is to [2:49] look toward the sun. Never look at any [2:52] light, sunlight or otherwise, that's so [2:54] bright that it's painful to look at [2:55] because you can damage your eyes. But [2:57] for this morning sunlight viewing, it's [3:00] best to not wear sunglasses. That's [3:02] right, to not wear sunglasses. It is [3:04] absolutely fine to wear eyelasses or [3:07] contact lenses, so-called corrective [3:09] lenses. In fact, those will serve you [3:11] well in this practice or this tool [3:13] because they will focus the light onto [3:14] your neural retina and onto those [3:16] melanopsin intrinsically photosensitive [3:17] ganglen cells. This is grounded in the [3:20] core of our physiology. There are [3:22] literally hundreds if not thousands of [3:23] quality peer-reviewed papers showing [3:25] that light viewing early in the day is [3:28] the most powerful stimulus for [3:29] wakefulness throughout the day and it [3:32] has a powerful positive impact on your [3:34] ability to fall and stay asleep at [3:35] night. So, this is really the [3:37] foundational power tool for ensuring a [3:40] great night's sleep and for feeling more [3:42] awake during the day. If you wake up [3:44] before the sun is out, you can and [3:47] probably should flip on artificial [3:49] lights in your internal home environment [3:51] or apartment or wherever you happen to [3:53] live. If your goal is to be awake, [3:55] right? If you wake up at 4 in the [3:56] morning and you need to be awake, well, [3:57] then turn on artificial lights. If [3:59] you're asking whether or not turning on [4:00] artificial lights can replace sunlight [4:02] at those hours. Unfortunately, the [4:04] answer is no. Unless you have a very [4:07] special light, we'll talk about what [4:09] kind of light. The bright artificial [4:11] lights in your home environment are not, [4:14] I repeat, are not going to be [4:15] sufficiently bright to turn on the [4:19] cortisol mechanism and the other wake up [4:21] mechanisms that you need early in the [4:23] day. The diabolical twist, however, is [4:25] that those lights in your home or [4:26] apartment or even on your phone are [4:29] bright enough to disrupt your sleep if [4:32] you look at them too late at night or in [4:34] the middle of the night. So, there's [4:35] this asymmetry in our retinal, our eye [4:38] biology, and in our brains biology [4:40] whereby early in the day, right around [4:42] waking, you need a lot of light, a lot [4:44] of photons, a lot of light energy. And [4:46] artificial lights generally just won't [4:48] accomplish what you need them to [4:50] accomplish. But at night, even a little [4:53] bit of artificial light can really mess [4:55] up your so-called circadian, your [4:57] 24-hour clocks and all these mechanisms [4:59] that we're talking about. On cloudy [5:00] days, you especially need to get [5:02] outside. I repeat, on cloudy days, [5:05] overcast days, you especially need to [5:06] get outside and get sunlight. You just [5:08] need to get more of it. Now, how much [5:10] light and how much light viewing do you [5:12] need? This is going to vary depending on [5:14] person and place. I mean, literally [5:16] where you live on Earth, whether or not [5:17] there's a lot of tree cover, whether or [5:19] not you're somebody who has sensitive [5:21] eyes or less sensitive eyes, it's really [5:23] impossible for me to give an absolute [5:25] prescriptive, but we can give some [5:26] general guidelines. In general, on a [5:28] clear day, meaning no cloud cover or [5:30] minimal cloud cover, you want to get [5:32] this sunlight exposure to your eyes for [5:36] about five minutes or so. Could be 3 [5:39] minutes one day, could be 7 minutes the [5:40] next day. about 5 minutes. On a day [5:44] where there's cloud cover, so the sun is [5:46] just peeking through the clouds or it's [5:47] more dense cloud cover, you want to get [5:50] about 10 minutes of sunlight exposure to [5:53] your eyes early in the day. And on days [5:55] that are really densely overcast or [5:57] maybe even a rainy, you're going to want [5:59] to get as much as 20 or 30 minutes of [6:02] sunlight exposure. Just don't try and [6:04] get this sunlight exposure through a [6:06] windshield of a car or a window, whether [6:09] or not it's tinted or otherwise. it [6:10] takes far too long. It's simply not [6:13] going to trigger the relevant [6:14] mechanisms. Now, if you live in a part [6:16] of the world where it's extremely dark [6:18] and overcast or the weather won't let [6:19] you outside or you live in a cave, there [6:22] are sunlight simulators or daylight [6:24] simulators that you can purchase. Those [6:26] are quite expensive in general. [6:28] Therefore, I suggest cheaper options [6:31] that work just as well because they get [6:33] just as bright. things like ring lights [6:35] that are sold in order for people to [6:37] take selfies and this kind of thing. A [6:40] LED tablet will work pretty well. I [6:42] actually have one of those and I put it [6:43] on my desk all morning even though I [6:45] still get outside and look at sunlight [6:47] first thing in the morning. Again, also [6:50] especially I should say on cloudy days. [6:52] Many of our listeners live in locations [6:53] throughout the world where for instance [6:54] during the winter it gets very very [6:56] dark. So they can't get sufficient [6:57] sunlight. But get that morning light, [7:00] ideally from sunlight, and take into [7:02] account all the specific points that [7:04] I've given you here. When you start [7:06] doing this, you'll notice that your body [7:09] will start to feel more energized and it [7:11] will feel more energized more quickly. [7:14] You'll actually start to notice this [7:16] mechanism kicking in each day, [7:17] especially if you're paying attention to [7:18] your physiology. It's that diffuse, very [7:20] bright sunlight, that photon energy that [7:22] you really want. That's going to set all [7:24] the rhythms of your brain and body in [7:25] the proper way. Not just that cortisol [7:28] peak, but it's going to trigger proper [7:30] metabolism. It's going to set a timer [7:32] for you to be able to fall asleep about [7:34] 16 hours later. It's also going to [7:35] suppress any melatonin, a hormone that [7:38] makes you sleepy that happens to be [7:39] swimming around in your bloodstream at [7:41] the time you wake up. It does a number [7:43] of other things too, including interact [7:44] with the adenosine system and kind of [7:46] wash out some of the adenosine that [7:48] might still be residual if you didn't [7:49] sleep enough. Fundamentally speaking, [7:52] get that morning sunlight viewing. I [7:54] promise you will be grateful that you [7:57] did. It makes everybody feel better, [7:59] feel more alert, and it will greatly [8:01] assist with your ability to fall and [8:03] stay asleep later that night. You will [8:05] also want to leverage not just light but [8:08] temperature as a tool. If you are [8:11] inclined, it would be wise to try and [8:13] increase your core body temperature a [8:16] bit more quickly than it would otherwise [8:19] if you were to just, you know, shuffle [8:20] around outside, get your sunlight, maybe [8:22] read a little bit, etc. And there are [8:24] two main ways you can do that. The first [8:25] way is to get into cold water of some [8:29] sort. So this could be a cold shower of [8:30] anywhere from 1 to 3 minutes. This could [8:32] be an ice bath if that's your thing. It [8:34] could be a cold tub or if you own a a [8:36] cold tub uh that's specifically designed [8:39] for deliberate cold exposure. Get under [8:41] some cold water. 1 to 3 minutes of cold [8:43] water exposure will wake you up because [8:44] of that adrenaline release. And and I [8:47] want to highlight the and it will serve [8:50] to increase your core body temperature. [8:53] That's right. If you put something cold [8:54] on the surface of your body, your brain, [8:56] a little cluster of neurons in the [8:57] so-called medial preoptic area, act as a [9:00] thermostat and say, "Ah, the external of [9:02] my body is cold and therefore I'm going [9:04] to heat up my core body temperature." [9:06] So, this is a little bit paradoxical. [9:07] People think, oh, if you get into cold [9:09] water or an ice bath, your body [9:10] temperature is going to drop. And [9:11] indeed, that's true. If you stay in for [9:12] a while, but if you just get in for [9:14] about 1 to 3 minutes or under the cold [9:16] shower for 1 to 3 minutes, your core [9:17] body temperature will increase. So, this [9:20] is great for waking up. And we have [9:23] exercise. One of the best ways to [9:24] increase your core body temperature [9:26] early in the day is to do exercise. I [9:28] always say the best time to exercise, at [9:30] least what the research points to, is [9:32] immediately when you wake up in the [9:33] morning. It could be a walk. So you can [9:35] get your sunlight exposure while you're [9:37] taking a walk first thing in the [9:38] morning. It could be a light jog. It [9:40] could be skipping rope. But try and get [9:42] your core body temperature increased [9:44] first thing in the morning. And a great [9:46] way to do that is with a cold water and [9:49] or with exercise. And again, it doesn't [9:51] have to be your full-blown workout for [9:53] the day if you're doing workouts [9:55] consistently, which I hope everybody is [9:56] because everybody really should [9:58] exercise. Right now, you'll notice we're [9:59] only focused on this early part of the [10:01] day. And you might be saying, "Wait a [10:02] second. I thought this was an episode [10:03] about tools for sleep." Well, everything [10:05] that we're talking about doing in these [10:07] first 60 to 90 minutes of the day really [10:10] set in motion a wave of biological [10:13] cascades that carry through the entire [10:15] day and into the evening and into the [10:17] night and really do serve to optimize [10:19] sleep. So just hang in there with me. So [10:20] the next category of tool for use early [10:23] in the day is caffeine. You do not have [10:25] to drink caffeine. So what I'm about to [10:27] describe are ways to leverage caffeine [10:29] use to optimize sleep and wakefulness if [10:32] you are comfortable with caffeine. [10:34] Caffeine is something that a lot of [10:35] people consume early in the day. How [10:37] much depends on your tolerance and [10:40] there's a lot of individual variability [10:41] here. Again, caffeine is a denosine [10:43] antagonist or effectively works as a [10:45] denosine antagonist and limits [10:47] sleepiness. And for many people, [10:49] shifting that caffeine intake from [10:51] immediately after waking in the morning [10:52] to 90 to 120 minutes gives them a much [10:55] longer arc of energy throughout the day [10:57] and they don't feel the need to drink [10:59] more caffeine later in the afternoon. If [11:02] you do drink caffeine later in the [11:03] afternoon, really try and limit the [11:05] total amount or drink decaf. Certainly [11:07] keep the total amount to less than 100 [11:10] milligrams if you are interested in [11:11] getting into the best possible sleep. [11:13] And I say this knowing that many people, [11:15] including myself, can drink a double [11:16] espresso with 200 milligrams of caffeine [11:19] or more at 5:00 p. p.m. or even 6 PM or [11:21] after dinner and still quote unquote [11:24] fall asleep fine or still sleep fine. [11:26] There are more and more papers all the [11:27] time that point to the fact that [11:28] caffeine intake late in the day after 4 [11:32] p.m. that is can really disrupt the [11:34] architecture of your sleep. So you might [11:35] think you're sleeping well, but you're [11:37] not sleeping nearly as well as you could [11:38] if you avoided caffeine in those [11:40] afternoon hours. Now, some of you might [11:42] be doing your main bout of exercise [11:44] first thing in the morning and you want [11:46] your caffeine before that bout of [11:47] exercise. In that case, I say go for it. [11:50] I absolutely respect the fact that [11:52] people have different work schedules, [11:54] kids schedules, etc. So, if you want to [11:57] do some or none or all these tools, [11:58] that's really up to you. I'm just [12:00] providing them to you in the simplest [12:02] form that I can possibly provide them. [12:04] Now, the other lever or tool that you [12:06] have available to you is food. Not just [12:08] what you eat, but when you eat. And it [12:10] turns out that if you eat early in the [12:12] day, you support a biological clock [12:15] mechanism that will make you more alert [12:17] early in the day. That said, many people [12:19] choose to fast in the early morning [12:21] hours of the day or in the first part of [12:23] the day. I'm one such person. I [12:24] generally don't ingest any food until [12:27] about 11:00 a.m. or 12:00 noon. [12:29] Sometimes I'll have breakfast. If people [12:30] are meeting for brunch or breakfast, I [12:32] will have breakfast for social reasons [12:34] every once in a while, but most of the [12:35] time I don't eat until about lunchtime. [12:38] However, some people are really hungry [12:40] when they wake up in the morning. Just [12:41] know that if you eat early in the day, [12:44] you are further triggering an increase [12:46] in metabolism and in temperature that [12:49] will make you more alert. So, you don't [12:51] have to eat early in the day, but you [12:54] can start to see how these different [12:55] tools layer together. Sunlight viewing, [12:57] exercise, cold water, eating, many of [13:00] them are converging on the same [13:01] mechanisms. In fact, when you drink [13:02] caffeine, there's also a small increase [13:04] in body temperature due to the [13:05] adrenaline increase that it stimulates. [13:07] So all of these things can be layered on [13:09] top of one another or you can use them [13:11] individually or think about them [13:12] individually. Now food is an interesting [13:14] lever or tool because it's not just [13:17] about when you eat, but it's also about [13:18] what you eat. And I've talked a lot [13:21] about eating for energy and what that [13:23] means in terms of caloric energy versus [13:25] neural energy, etc. in previous podcast [13:27] episodes. We're not going to focus on [13:28] that now because that's very nuanced. [13:31] All that said, if you eat a very large [13:33] meal, it doesn't matter if you slept [13:36] terrifically well 10 hours the night [13:38] before or if you are about to go to [13:40] sleep or if it's the middle of the [13:42] afternoon, if your gut is full of food, [13:44] there's just a large volume of food in [13:46] your gut, it's going to divert a lot of [13:49] blood and other critical resources away [13:52] from other organs of your body, in [13:54] particular your brain, and you're going [13:55] to be sleepy after eating a big meal. So [13:57] this is sort of a duh, but I think [13:59] oftentimes in the discussions about what [14:01] to eat for energy, people neglect to [14:04] consider food volume as a strong [14:06] parameter or variable in that [14:08] discussion. So if you eat a huge [14:10] breakfast, it's likely that you're going [14:11] to be tired immediately after eating [14:13] that breakfast, unless of course you [14:14] exercise very hard prior to that and you [14:17] metabolize all that food very quickly. [14:18] So if you do decide to eat in the first [14:20] few hours of the morning, just [14:21] understand that you are setting or you [14:23] are helping to set a food entrained as [14:26] it's called circadian clock. Light, [14:30] temperature, timing of food intake, [14:32] movement, and exercise. All of these [14:34] things literally funnel in in a neural [14:38] sense. They funnel into this thing that [14:40] we call the circadian clock. and they [14:42] let that clock, that set of neurons, [14:44] predict when you are likely to be eating [14:47] and active and viewing sunlight the next [14:50] day and the next day and the next day. [14:51] So, what all these tools do is they [14:53] really set up a cascade. Think of it as [14:56] kind of a wavefront of wakefulness and [14:58] focus throughout the day. It'll take you [14:59] through the middle of the day in the [15:01] afternoon stages we'll talk about in a [15:02] few minutes, but really they take you to [15:05] this period that is about 5:00 p.m. [15:08] until your bedtime. A second critical [15:10] period in which you need to leverage [15:12] particular tools in order to get and [15:14] stay asleep optimally and to be able to [15:17] sleep through the night. So really, [15:19] there are three critical periods [15:20] throughout each 24-hour cycle. And [15:22] during each of those critical periods, [15:24] you're going to want to do as many [15:26] specific things as you can to optimize [15:28] your wakefulness and focus and mood [15:30] throughout the day and your sleep at [15:32] night. The first critical period is the [15:34] one that we've been talking about up [15:34] until now. Things like morning sunlight, [15:36] viewing caffeine, 90 to 120 minutes [15:38] after waking, exercise, and so on. And [15:40] it really encompasses the time from [15:42] which you wake up until about 3 hours [15:45] after waking. The second critical period [15:47] is the time throughout the day and [15:50] afternoon leading into evening. So you [15:52] may ask, what are the things that you [15:53] can do throughout the day, the middle of [15:55] your day and into the afternoon and [15:56] evening hours that are really going to [15:58] set you up for the best possible sleep [15:59] later that night? Well, there are a few [16:02] dos and there are a few don'ts. First of [16:04] all, be careful about ingesting too much [16:06] caffeine throughout the middle of the [16:08] day. That's kind of an obvious one for [16:09] the reasons that we talked about [16:10] earlier. Second of all, if you are a [16:12] napper, and I raise my hand now for [16:14] those of you listening, I'm raising my [16:15] right hand because I love naps. I've [16:17] always loved naps. Should you nap? [16:19] Should you not nap? That's a question [16:21] that I get asked a lot and that I asked [16:22] Dr. Matthew Walker when he was a guest [16:24] on this podcast. Here was his answer. [16:26] And here's what the data support. It is [16:28] fine to nap in the afternoon, but don't [16:31] nap so late in the day or for so long [16:33] that it disrupts your ability to fall [16:36] and stay asleep at night for your major [16:38] sleep bout. I should also say you do not [16:40] have to nap. It's kind of an interesting [16:42] phenomenon that happens on these [16:44] podcasts and on social media where we'll [16:46] talk about naps and the fact that naps [16:47] are great and don't make them longer [16:49] than 90 minutes, but then all the [16:51] non-nappers get really worried like, [16:53] "Wait, am I supposed to nap? I don't [16:54] like naps. I wake up groggy." You do not [16:56] have to nap. In fact, if you can make it [16:58] through your whole day without napping, [16:59] great. More power to you. So, this [17:01] critical period throughout the day is [17:03] one in which most people are doing a lot [17:04] of stuff. They're emailing and picking [17:06] up kids and they're exercising and [17:07] they're commuting and doing all sorts of [17:09] things, taking phone calls and Zooms, [17:11] etc. But if you can get that period of [17:13] deep relaxation through a nap or NSDR, [17:16] that's going to serve you well. Try not [17:18] to drink too much caffeine, certainly no [17:19] more than 100 milligrams of caffeine [17:22] after 4 p.m. if your goal is to fall [17:24] asleep at a reasonably normal time. And [17:26] for those of you that exercise in the [17:28] afternoon, understand that if you [17:31] exercise very intensely, so this might [17:33] be weight training or running or some [17:34] other very intense exercise, typically [17:37] that's going to further increase your [17:39] body temperature and it's going to [17:40] so-called delay your circadian clock. [17:43] It's going to make it such that you want [17:45] to fall asleep a little bit later, maybe [17:48] even a lot later. So if you're [17:49] exercising in the afternoon or evening [17:52] and that's the only time you can [17:53] exercise or that's the time that you [17:54] prefer to exercise, great. Just know [17:56] that you are delaying your circadian [17:58] clock, you are making it such that you [18:00] will naturally want to go to sleep later [18:02] and wake up later. Contrast that with if [18:04] you exercise early in the day, say [18:07] immediately after waking up or in the [18:09] first 0 to 4 hours after waking. In most [18:13] cases, that's not going to shift your [18:14] circadian clock much. This critical [18:17] period two or second critical period I [18:19] should say during the middle of the day [18:20] is a time in which you should be doing [18:22] certain things and avoiding doing [18:23] certain things. So that raises the [18:24] question of whether or not you should [18:25] also be getting a lot of light in [18:27] particular sunlight throughout the day. [18:28] Now on the face of it you might just [18:30] think yes you know sunlight's great [18:31] provided we're not getting a sunburn and [18:33] we're not staring at the sun and [18:34] damaging our eyes we should get as much [18:36] sunlight as we possibly can. However, [18:39] because light is such a powerful [18:40] stimulus for controlling the timing of [18:42] your sleepfulness or sleepiness, I [18:44] should say, and wakefulness, [18:47] we might want to be cautious about how [18:48] much light we are viewing in the [18:50] afternoon, in particular, in the early [18:52] evening hours. Well, turns out it's not [18:55] so straightforward viewing. So, sunlight [18:57] to the eyes, sunlight in the late [18:59] afternoon and evening hours. So again, [19:01] depends on time of year, depends on [19:03] location that you happen to be in. But [19:05] getting some sunlight in your eyes for [19:06] again maybe 5 or 10, maybe 30 minutes [19:10] depending on how much cloud cover there [19:12] is. Doing that in the afternoon serves [19:14] an additional beneficial purpose, which [19:17] is you inoculate your nervous system [19:19] against some of the negative effects of [19:22] bright artificial light or even dim [19:24] artificial light in the nighttime hours [19:28] between 10 p.m. and 4:00 a.m., which is [19:30] really critical period 3. And we'll talk [19:31] about what to do and what to not do [19:33] during critical period 3 of every [19:35] 24-hour cycle. But to make it very clear [19:37] what I'm saying here, get that morning [19:39] sunlight in your eyes, but also get some [19:42] sunlight in your eyes in the late [19:44] afternoon and evening hours when the sun [19:46] is at so-called low solar angle, when it [19:47] starts to descend in the sky. Getting [19:49] that sunlight in your eyes in the late [19:51] afternoon and evening signals to that [19:54] clock that it's evening time and that [19:57] sleep is coming. It also serves as a [20:00] second anchor that tells your brain and [20:02] body, hey, it's evening. The sun is [20:04] descending. Those yellows and blues and [20:07] oranges that you see in the evening [20:08] sunsets, those signal to your brain and [20:10] body that evening is there and that [20:12] nighttime is coming. And they're really [20:14] establishing a second reference point or [20:16] wavefront of biological signals that are [20:19] going to optimize your nighttime hours [20:21] and your transition into really terrific [20:23] sleep. So now let's talk about what I'm [20:25] calling critical period three of each [20:28] 24-hour cycle. So this would be the [20:29] period of time of late evening. So, it [20:32] might be 6:00 p.m. for some, depending [20:34] on when you go to sleep, or 7:00 p.m. [20:36] extending into the hours in which you [20:39] decide to get into bed and go to sleep. [20:41] And then throughout the night, there are [20:42] a number of things that you're going to [20:44] want to do, and there are a number of [20:45] things that you are going to want to [20:47] avoid doing in order to optimize your [20:49] sleep. First of all, you're going to [20:51] want to avoid bright artificial lights [20:54] of any color. Once the sun goes down, [20:57] you would be wise to try and dim the [20:59] lights in your indoor environment. If [21:01] you are going to use light at night, and [21:03] most people do, I would encourage you to [21:06] use as little artificial light as is [21:08] required to carry out the activities you [21:10] need to require safely. If you're [21:12] watching a television show or you're [21:14] watching something on your computer, dim [21:16] that screen way, way down, as dim as [21:18] possible while still, of course, being [21:19] able to view what you need to view. That [21:21] bright light exposure will absolutely [21:23] quash any melatonin that happens to be [21:26] circulating in your brain and body. Now, [21:27] melatonin a lot of people think of as a [21:29] supplement, but melatonin is naturally [21:31] released as the evening comes about and [21:33] into the nighttime hours. It's a hormone [21:35] that makes you feel sleepy and allows [21:37] you to fall asleep. So, viewing bright [21:39] light in the late evening hours and [21:41] nighttime hours is really not good for [21:44] your sleep quality and your ability to [21:46] fall and stay asleep. So, for most [21:48] people, a simple rule of thumb is going [21:50] to be avoid bright artificial lights of [21:52] all colors and in particular overhead [21:55] bright artificial lights between the [21:56] hours of 10 p.m. and 4:00 a.m. Use only [21:59] as much light as is absolutely necessary [22:01] in order to carry out the routines and [22:03] activities you need to carry out safely. [22:06] Now, that's light, but as you recall, we [22:08] also have this tool related to [22:09] temperature. And you're probably not [22:12] going to be surprised that the way to [22:14] leverage temperature in the evening is [22:16] the exact opposite of the way that you [22:17] want to leverage temperature early in [22:19] the day. Early in the day, temperature [22:21] increases from cold showers or exercise, [22:23] etc. wake you up. What that means is [22:25] that taking a cold shower late at night [22:27] is probably a bad idea. Rather, taking a [22:30] nice hot bath or a sauna you might think [22:32] would heat up your body. And indeed, [22:34] that's what happens if you stay in a [22:35] very long time. But if you do hot tub or [22:37] a hot bath or a sauna in the evening and [22:40] you don't stay in for more than 20 or 30 [22:41] minutes and you get out, you take maybe [22:43] a coolish shower or a warm shower, then [22:46] what happens is there's a compensatory [22:48] cooling off of your core body [22:49] temperature for the reasons we discussed [22:51] earlier and your body temperature will [22:52] drop by 1 to 3° and it will make it much [22:55] easier to get into sleep. So if you're [22:57] somebody that enjoys hot baths, hot [22:58] showers or hot tubs, evening and [23:01] nighttime is going to be the best time [23:02] to do that if your goal is to facilitate [23:05] sleep. Similarly, you should try and [23:07] make your sleeping environment pretty [23:08] cool, if not cold. Now, that doesn't [23:10] mean you need to be cold while you're [23:12] asleep. You can get under as many [23:14] blankets as you need, but it's a good [23:15] idea to make your sleeping environment [23:17] cool. In fact, drop the temperature in [23:19] that sleeping environment by at least [23:20] 3°. You'll be happy that you did. You're [23:23] going to want to sleep in a relatively [23:24] cool or cold sleeping environment and [23:26] then layer on the blankets as needed to [23:29] stay asleep. If you lower the [23:31] temperature in your sleeping [23:32] environment, so lower the temperature in [23:33] that room or use a controllable mattress [23:36] cover that can cool down like eight or [23:38] something of that sort, it's naturally [23:39] going to make your sleeping environment [23:41] cooler. And if you're too warm under the [23:44] blankets, all you have to do is extend a [23:45] hand or a foot out from under those [23:47] blankets. Whereas, if the sleeping [23:49] environment that you're in is too warm, [23:50] there's very little you can do to cool [23:52] off besides push off those blankets. But [23:54] if the room is too warm, well, what are [23:56] you going to do? You'd probably have to [23:57] put your hands into some cool water, [23:58] take a coolish shower or something for a [24:01] couple of seconds. That's not very [24:02] practical. I would be remiss if I didn't [24:04] touch on alcohol and CBD and THC. Many [24:08] places, but not all. THC is illegal, [24:11] although there are medical uses and some [24:13] places it's um decriminalized. Other [24:15] places it's legal. Alcohol, of course, [24:17] is consumed almost as frequently as [24:20] caffeine is consumed. The sleep that one [24:22] gets after drinking alcohol is greatly [24:25] disrupted sleep. THC and alcohol do help [24:29] some people fall asleep and maybe even [24:32] stay asleep. The architecture of that [24:33] sleep is suboptimal compared to the [24:36] sleep they would get without alcohol or [24:38] THC in their system. So, I'm not here to [24:40] tell you what to do or not to do. I'm [24:42] certainly not um the substance police. [24:45] That's not my role. I'm just reporting [24:46] to you the biology. If your sleep is not [24:49] restoring you to the extent that you [24:51] feel it should or if you are regularly [24:53] relying on a drink or two in order to [24:56] fall asleep or THC in order to fall [24:58] asleep that is disrupting your total [25:01] pattern of sleep. Okay? So you've done [25:03] everything correctly up until now. You [25:05] got your morning routine from critical [25:06] period one. You got your afternoon [25:08] routine. You saw some sunlight in the [25:10] afternoon. You avoided caffeine in the [25:12] eight hours or 10 hours before bedtime. [25:14] You're not drinking alcohol. you've [25:16] cooled down the room, uh you're doing [25:18] all these things right, you've dim the [25:19] lights, etc., etc. What else can we do [25:22] in order to optimize our sleep? I always [25:24] say behavioral tools first, then look to [25:28] nutrition, then if necessary, look to [25:30] supplementation, and then if still [25:32] necessary, look to prescription drugs, [25:35] obviously prescribed by a [25:37] board-certified physician. There are [25:38] supplements that for most people will [25:40] greatly improve their ability to fall [25:43] and stay asleep. And the three main [25:45] supplements in that category or that kit [25:48] of sleep supplements, and I've talked [25:50] about these before, are magnesium [25:52] thriionate. So, T h reo n a t e, [25:57] apagenine, api g- e n i n, and theonine. [26:01] T h e a n i n e. Theonine. You don't [26:04] necessarily need to take all three. [26:06] Although many people get a synergistic [26:08] effect from taking all three. You may [26:09] not even need to take even one. What I [26:12] recommend is that if you're already [26:14] doing all the behavioral tools regularly [26:16] and you're still having trouble falling [26:18] asleep and staying asleep, well then you [26:21] might try one of the supplements within [26:24] this sleep stack. They do have fairly [26:26] wide margins for safety. Although I [26:27] should also say anytime you're going to [26:30] add or remove something from your [26:32] supplement protocol, your nutritional [26:33] program, you definitely want to talk to [26:35] your physician. I don't just say that to [26:36] protect us. I say that to protect you. [26:38] For most people, the margins of safety [26:39] on these things are going to be pretty [26:40] broad. For some people, the dosages of [26:42] any one or several of the supplements I [26:44] mentioned will be zero. That is, you [26:46] won't need them in order to get and stay [26:48] asleep most nights of your life. For [26:50] many people, however, taking 145 [26:53] milligrams of magnesium 3en8ate can be [26:56] very beneficial. Some people need to go [26:58] a little higher. Some people need to go [26:59] a little bit lower. 50 milligrams of [27:02] apagenine. And again, you could just [27:04] take the apagenine on its own. And 100 [27:07] to 400 millig of theanine taken again [27:11] alone or in combination with the other [27:13] supplements mentioned in this stack many [27:15] people find allows them to get really [27:17] drowsy and fall asleep sleep really [27:19] deeply and they feel much more refreshed [27:21] the next day and they don't have a [27:22] groggginess. About 5% of people report [27:26] that magnesium 3 and8 really disrupts [27:29] their gut. It gives them diarrhea or [27:31] gastric distress in which case don't [27:32] take it. Now in a slightly different [27:34] way, many people who can tolerate [27:37] magnesium 3 and8 or really thrive on [27:39] magnesium 3 and8 and like epigenine [27:42] might find that theanine even at the [27:45] lowest dose of 100 milligrams because [27:46] again the range is 100 to 400 milligrams [27:48] that theanine gives them such vivid [27:51] dreams that they actually find it [27:52] disruptive or they wake up and in the [27:54] middle of the night or they find that [27:55] the sleep that they're getting is kind [27:56] of anxietyridden because of the [27:58] intensity of those dreams. So some [28:00] people might choose to leave theanine [28:01] out of the sleep stack and just take [28:03] magnesium 3in8 or rapenine. Again, some [28:05] people might leave magnesium 3 and8ate [28:07] out of the sleep stack. All of this is [28:09] really about finding the supplementation [28:11] protocol that's ideal for you. I should [28:13] mention that whether or not you're [28:14] taking one or two or three of the [28:16] components of the sleep stack. The ideal [28:18] time to take those is 30 to 60 minutes [28:20] before bedtime. That sleep stack can be [28:22] very beneficial to people. And I do [28:24] think that it's preferable to melatonin. [28:26] First of all, melatonin is a hormone [28:28] that you indogenously make. The dosages [28:30] of melatonin that are contained in most [28:32] commercial products is far far far [28:34] greater than what we would make [28:35] indogenously. So, it's really supra [28:38] physiological. So, that's of concern [28:40] because melatonin is not just [28:41] responsible for making us sleepy and [28:44] fall asleep. It also does things like [28:47] interacts with other hormone systems, [28:49] testosterone and estrogen, even in the [28:50] puberty system in kids. Is taking [28:52] melatonin every once in a while a [28:54] problem for adjusting to jet lag, etc.? [28:56] Probably not. I would even say no. But [28:58] taking it chronically over time, [29:00] especially kids taking it chronically [29:02] over time, can potentially be [29:03] problematic. I do want to mention a [29:05] couple of broad contour tools that will [29:08] impact your ability to sleep really well [29:11] on a consistent basis. And the one that [29:13] impacts the most number of people is [29:15] weekends. Turns out that most everybody [29:18] feels the impulse to sleep in on the [29:20] weekend, especially if they've been out [29:21] late the night before. However, the data [29:24] show that keeping relatively consistent [29:27] sleep and wake times is really going to [29:29] enhance the quality and depth of your [29:31] sleep. So, if you stay out late one [29:32] night, sure, you might allow yourself to [29:35] sleep in an extra hour or so, but you [29:37] should really try to avoid sleeping in [29:39] longer than an hour beyond your normal [29:43] wake up time. it would be better to wake [29:44] up at a consistent time plus or minus an [29:46] hour and get a nap in the afternoon [29:48] provided that nap again isn't too long. [29:51] Now, a couple of final points and [29:52] additional tools that I think are going [29:54] to be useful to everybody in particular [29:56] people who have young children or are [29:59] following a shift work schedule or who [30:02] are experiencing jet lag. Keep in mind [30:05] jet lag can be due to travel, which is [30:07] obvious, but jet lag can also be due to [30:10] getting woken up in the middle of the [30:11] night, right? Your body doesn't know the [30:12] difference between flying to a new time [30:14] zone and getting woken up in the middle [30:16] of the night. The tool that I'd like to [30:18] offer you is an understanding of [30:19] something called temperature minimum. [30:21] And I'm going to make this as simple as [30:23] possible, and I'm confident that [30:24] everyone can understand this, even if [30:25] you don't have any science background. [30:27] Here's the question you need to ask [30:28] yourself. What is your typical wake up [30:32] time? If your typical wake up time most [30:34] days is 7 a.m., well, then your [30:37] temperature minimum is 5:00 a.m. That's [30:39] right. Your temperature minimum is not a [30:41] temperature. It's a time within your [30:43] 24-hour cycle. Approximately 2 hours [30:46] before your typical wake up time, your [30:48] body is at its lowest temperature that [30:50] it will ever be in the 24-hour cycle. [30:53] That's why it's called your temperature [30:54] minimum. Here's what you need to know [30:56] about your temperature minimum. If you [30:58] view bright light, exercise or drink [31:02] caffeine or all of the above in the two [31:05] to four hours before your temperature [31:08] minimum, that will delay your clock. [31:11] What that means when I say delay your [31:13] clock is it will make you want to go to [31:15] sleep later and wake up later the next [31:18] night. Okay, so let's run this exercise [31:20] for you, the person waking up at 7 a.m. [31:22] on a regular basis. I can predict with [31:25] almost certainty that your body is going [31:27] to be at its lowest temperature at 5:00 [31:30] a.m. So, what that means is that if you [31:32] get up at 3:00 a.m. or at 4:00 a.m. and [31:36] you flip on bright lights in your house [31:38] or in your bathroom or you have a cup of [31:40] coffee or you do any kind of exercise or [31:42] you get up and head to the airport, the [31:45] mechanisms in your brain and body that [31:47] control timing of sleep and timing of [31:49] waking will shift. They will delay. It's [31:51] as if you put your clock on hold for a [31:54] little while and then let it start [31:55] again. Okay, that's the simplest way I [31:57] can describe it. And you will tend to [31:58] want to go to sleep later and wake up [32:01] later the following night. Now, the [32:04] opposite is true if you view bright [32:07] light, drink caffeine, or exercise or [32:10] socialize, I should say, in the hours [32:13] immediately after your temperature [32:15] minimum. So for you in this example, the [32:17] person who's waking up at 7:00 a.m., [32:19] your temperature minimum is 5:00 a.m. If [32:21] you view bright light, exercise, maybe [32:23] have a snack, maybe not, or socialize, [32:26] move about at 5:30 or 6:00 a.m. or 7:00 [32:30] a.m., that will tend to phase advance [32:33] your clock. It will tend to basically [32:36] make you want to go to bed earlier and [32:38] wake up earlier the following night. [32:39] Now, I use this example of a person who [32:41] wakes up typically at 7:00 a.m. whose [32:43] temperature minimum is 5:00 a.m. But of [32:45] course, you need to adjust that for [32:47] yourself if you're somebody who wakes up [32:48] at 9:00 a.m. or at 5:00 a.m., etc. Why [32:50] do I offer this as a tool? Well, this is [32:52] an immensely powerful tool if, for [32:54] instance, you are headed to a time zone [32:56] where you need to go to bed earlier and [32:58] wake up earlier once you arrive in that [33:00] time zone. What it means is in the day [33:01] or two before you leave, you can force [33:04] yourself to exercise, drink caffeine, [33:08] maybe even to eat a meal early in the [33:10] morning, or maybe you still fast early [33:11] in the morning. That's really up to you. [33:13] But you force yourself to do the act the [33:15] activities that are going to phase [33:17] advance your clock. Whereas, if you're [33:19] traveling to a time zone where you are [33:21] going to need to go to sleep much later [33:23] and you're going to need to wake up much [33:26] later, even a little bit later, you can [33:28] do those things in the hours prior to [33:30] your temperature minimum. And I should [33:33] say for everybody, people who are doing [33:35] jet who are jetlagged and engaged in [33:38] shift work or not, but just for [33:39] everybody, if you need to be awake in [33:42] the middle of your sleep cycle, you [33:43] know, you're feeding a baby or you're um [33:46] you're taking care of a loved one or you [33:47] need to do something that's critical or [33:48] you need to work, use red light. Okay. [33:51] Now, for shift workers who really are [33:53] trying to stay awake all night and sleep [33:55] all day, this is not going to be ideal. [33:57] But for people that for instance need to [33:59] stay up really late one night or wake up [34:01] especially early like 3:00 a.m. to [34:02] prepare for an exam that you're just not [34:04] ready for or to head to the airport etc. [34:07] Using red light has been shown to allow [34:10] people to be awake enough that and [34:11] obviously see what they need to see in [34:13] order to perform their activities safely [34:15] but it does not seem to disrupt the [34:17] cortisol rhythm that is the healthy [34:20] normal cortisol rhythm. Okay. So, that's [34:22] a lot of information and a lot of tools, [34:24] and I really want to encourage everybody [34:25] to get your behaviors right, get your [34:27] nutrition right for you. I promise that [34:29] if you start to implement some or [34:31] ideally all of these tools, the quality [34:34] of your sleep will increase [34:35] tremendously. And of course, in doing [34:38] so, the quality of your daytime [34:39] alertness and your ability to focus will [34:41] improve tremendously. Again, sleep is [34:44] the absolute foundation of your mental [34:47] health, your physical health, and your [34:48] performance in all endeavors. And last, [34:51] but certainly not least, thank you for [34:53] your interest in science. [34:55] [music]