Dr. Samer Hattar: Timing Light, Food, & Exercise for Better Sleep, Energy & Mood

Introduction

In this section, Andrew Huberman introduces Dr. Samer Hattar as his guest on the Huberman Lab Podcast. Dr. Hattar is the Chief of the Section on Light and Circadian Rhythms at the National Institute of Mental Health in Bethesda, Maryland.

Introducing Dr. Samer Hattar

• Andrew Huberman introduces Dr. Samer Hattar as his guest on the podcast.

• Dr. Hattar was part of a group that discovered light-sensing neurons in the eye that set the circadian clock.

• Light regulates our sleep, immune system, mood, mental health, metabolism, feeding and many other important processes.

• Dr. Hattar presents a new model of how light, activity and feeding rhythms converge to support optimal health.

Importance of Aligning Sleep Schedule with Activity Schedule

In this section, Dr. Samer Hattar answers questions about aligning sleep schedule with activity schedule such as exercise.

Aligning Sleep Schedule with Activity Schedule

• Aligning sleep schedule with activity schedule is essential for optimal health.

• When sleep and activity schedules are not aligned correctly it can lead to negative impacts on mental and physical health.

• Specific protocols are presented to deal with shifts in day length and shifts in activity to optimize sleep and wellbeing.

Sponsors: ROKA & InsideTracker

In this section, Andrew Huberman thanks sponsors ROKA and InsideTracker for supporting the podcast.

ROKA Eyeglasses & Sunglasses

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• The glasses were designed with the science of the visual system in mind to make transitions seamless.

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InsideTracker Personalized Nutrition Platform

• InsideTracker analyzes data from your blood and DNA to help you better understand your body and reach your health goals.

• Blood tests are important for detecting factors that impact our immediate and long-term health.

InsideTracker and Magic Spoon

In this section, the host talks about two sponsors of the podcast, InsideTracker and Magic Spoon.

InsideTracker

• InsideTracker is a company that helps people optimize their health through behavioral practices like exercise, nutritional practices or supplementation.

• The company makes it easy for people to direct their health goals.

• To get 25% off any of InsideTracker's plans, visit InsideTracker.com/Huberman and use the code "Huberman" at checkout.

Magic Spoon

• Magic Spoon is a zero sugar, grain-free, keto-friendly cereal.

• It has 13 to 14 grams of protein and only four net grams of carbohydrates in each serving.

• It is low carbish or low carb and has only 140 calories per serving.

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How Light Impacts Mood, Learning, Feeding, Hunger and Sleep

In this section, Dr. Samer Hattar discusses how light impacts various functions in our body such as mood, learning, feeding hunger and sleep.

Circadian Clock

• Light has an aspect that is independent of conscious vision or image forming functions which regulates many important functions in our body.

• The most well-known function regulated by light is our circadian clock which shows up at every level from cells to tissues to behavior.

• Our circadian clock is an approximate day because it's not exactly 24 hours long but it still follows a daily rhythm even without information about feeding time or sleep time.

Impact on Mood and Hunger

• Light impacts our mood and hunger by regulating the release of hormones such as cortisol and melatonin.

• Cortisol is released in response to light exposure and helps us feel alert while melatonin is released in response to darkness and helps us feel sleepy.

Impact on Learning

• Light also impacts our ability to learn by affecting the function of neurons in the brain.

• Exposure to blue light can enhance cognitive performance, attention, and memory consolidation.

Impact on Sleep

• Light exposure at night can disrupt our sleep by suppressing melatonin production which makes it harder for us to fall asleep.

• Reducing exposure to blue light before bedtime can improve sleep quality.

The Importance of Circadian Rhythm

In this section, the speaker explains how the circadian rhythm works and why it is important for survival.

The Circadian Clock

• The circadian clock regulates our sleep-wake cycle.

• It is slightly longer than 24 hours, but we adjust to a 24-hour day through exposure to light.

• Our bodies are able to detect changes in light even subconsciously, which helps entrain our circadian clock to the solar cycle.

Importance for Survival

• Being out of sync with the solar cycle can have serious consequences for survival.

• Even a small difference in time can accumulate over days and lead to being out of phase with others in your species.

• This can cause jet lag-like symptoms and make it difficult to anticipate seasonal changes.

How We Detect Light

In this section, the speaker discusses how our eyes detect light and how this process helps regulate our circadian rhythm.

Photoreceptors in the Retina

• Our eyes are required for entraining our circadian clock to the solar cycle.

• There are two types of photoreceptors in the retina: rods and cones. These convert photon energy into electrical signals that allow us to see consciously.

Photoreceptors in the Brain

In this section, we learn about a subset of ganglion cells that are photoreceptors and relay light environment subconsciously to the areas in the brain that have and house the circadian clock.

Discovery of ipRCGs

• A small subset of ganglion cells are themselves photoreceptors.

• These photoreceptors relay light environment subconsciously to the areas in the brain that have and house the circadian clock.

• This discovery was made by Ignacio Provencio, David Berson, and others in 2000.

Ancient Form of Vision

• The system that connects the eyes to the rest of the brain is actually thought to be the most ancient form of vision.

• These same ipRCGs contribute a little bit to image formation but only limited aspects.

• They don't have specialized structures like other photoreceptors which makes them similar to ancient photoreceptors.

Melanopsin

• Melanopsin is an actual pigment that converts light into an electrical signal.

• It was first identified in frog melanophores where it drives their response to changes in color depending on light.

• It was later found expressed in retinal ganglion cells which opened up research on its role in regulating our body's circadian clock.

Seminal Experiment

• David Berson did a seminal experiment where he went to the brain where the central oscillator, which drives circadian rhythm in our bodies resides.

Light and Circadian Rhythms

In this section, the speakers discuss how light can control circadian rhythms and how people who are pattern vision blind can still have normal sleep-wake cycles.

Melanopsin Intrinsically Photosensitive Cells

• People who are pattern vision blind still have melanopsin intrinsically photosensitive cells that allow them to entrain onto the light-dark cycle.

• These individuals may not have problems in circadian photoentrainment and will have a normal sleep-wake cycle.

• Some of these people who are image blind usually get dry eyes, which causes them pain. Doctors used to think that removing their eyes would solve the problem, but it only made things worse as they started having cyclical sleep problems indicating that they were no longer entraining to the light-dark cycle.

Sleep Issues in Blind People

• Blind people often have issues with sleep because they don't realize that they too need to see light at particular times of day or night in order to match their schedule.

• It's important for blind people to understand how light affects their subconscious vision so that they can adjust their schedules accordingly.

Understanding Light Intensity

In this section, the speakers discuss how our system measures intensity subconsciously and why it's important for people to understand intensity.

Cones vs ipRCGs

• The cones themselves have an incredible ability to adapt to different light conditions, allowing us to see at all different conditions. However, ipRCGs measure intensity pretty well but don't adapt as well.

• Subconsciously, our system is used to measuring light intensity in a natural environment, and when we change these environments, we could really mess up ourselves.

Teaching People About Intensity

• It's important to teach people how to understand intensity because it's something that you have to explain to people.

• The speakers suggest doing an experiment where you use the lowest amount of light required to allow you to see comfortably.

Importance of Light for Circadian Rhythm

In this section, the importance of light for regulating the circadian rhythm is discussed. The speaker emphasizes the need for exposure to sunlight in the morning and explains how even on cloudy days, outdoor light is brighter than indoor light.

Getting Enough Light

• It's important to get outside and get enough light.

• Even on a cloudy day, outdoor light is brighter than indoor light.

• 15 minutes of daily exposure to sunlight should be sufficient to regulate the circadian rhythm.

• If you don't do it daily, you may want to increase your time spent outside.

Morning Sunlight and Sleep

This section discusses the impact of morning sunlight on sleep patterns. The speaker shares personal experiences and research findings that support the importance of morning sunlight for regulating sleep.

Importance of Morning Sunlight

• Morning sunlight seems to be very important for regulating sleep.

• Early morning light flashes can adjust total amount of sleep one gets.

• Camping experiments have shown that exposure to natural light can reset the circadian clock.

Personal Experiences

• The speaker wakes up at 4:30am but doesn't turn on artificial lights because they know that sun will come up eventually.

• Looking at computer or phone screens may provide enough light in absence of natural sunlight.

Circadian Setting Behavior

In this section, the speaker discusses how to set your circadian rhythm by exposing yourself to sunlight. They provide general rules of thumb for different weather conditions.

Sunlight Exposure

• On a very bright day, 10-15 minutes of sun exposure is sufficient.

• On an overcast day, stay outside for half an hour or longer if it's darker out.

• If you're in a place with dense cloud cover and far north, use artificial light sources like light boxes until more information is available.

Bright Light Exposure

• The speaker recommends using bright light in the morning but doesn't give specific numbers.

• Using a 930 lux light pad until the sun comes out is recommended.

Effects of Sunlight Exposure

• Being exposed to bright light during the day will not be bad for you unless it's too hot outside.

• The human evolution from near the equator has made it hard to maintain physiological homeostatic function during high temperature times.

The Importance of Light in Our Sleep-Wake Cycle

In this section, the speaker discusses how evolution has adapted organisms to a certain light environment and how even small changes in light intensity can be measured by ipRCGs. The importance of regular exposure to sunlight is emphasized for maintaining a healthy sleep-wake cycle.

Evolutionary Adaptation to Light Environment

• Evolution has adapted organisms to a certain light environment.

• Other animals that have lived in areas with less sunlight have developed interesting adaptations for measuring even small changes in light intensities.

• IpRCGs are incredibly linear and can measure even very small changes in light intensity if the organism has the ability to do so.

Regular Exposure to Sunlight

• Regular exposure to sunlight is important for maintaining a healthy sleep-wake cycle.

• Even missing one day of regular exposure can cause delays in the sleep-wake cycle.

• During the pandemic, many people experienced disruptions in their sleep-wake cycles due to staying indoors and not getting enough sunlight.

Chronotypes and Health Issues

In this section, the speaker discusses chronotypes and how they affect an individual's intrinsic rhythm. Deviating from this rhythm can lead to mental and physical health issues.

Chronotypes

• Each person has an intrinsic rhythm that determines whether they are a morning person or night owl.

• People who go to bed late and wake up late have an overwhelmingly higher level of depression and failures compared to those who go to bed early and wake up early.

Health Issues

• Deviating from one's intrinsic rhythm can lead to mental and physical health issues.

• Discrimination against late risers may be a factor in society's preference for early risers.

The Relationship Between Light and Sleep

In this section, the speaker discusses how light affects sleep patterns and whether late waking is controlled by the light environment or intrinsic factors.

Late Sleepers

• The relationship between light and sleep is not that light affects you in a certain way, but rather it's the relationship that your body has decided.

• There are people who go to sleep at 7:00 p.m. and wake up at 1:00 a.m., which is called advanced phase sleep syndrome.

• People who suffer from advanced phase sleep syndrome may be high achievers but they suffer because of their sleeping pattern.

Circadian Rhythm

• The circadian system may not be as variable in the human population as we think.

• Once you get into a rhythm, it's hard to break out of that rhythm because if you start sleeping late and waking up late, you're not getting the morning sunlight.

• Getting morning sunlight is important to understand whether one is meant to be an early bird or a late person.

Measuring Intensity

• It's important to be educated about how to measure intensity since measuring devices are needed for accurate measurements.

• Free apps like Light Meter can help measure lux in the environment, but these apps can be complicated since they require pointing them to specific regions.

• Most people would need at least 10 times less light than they use at night to see.

Importance of Morning Light Viewing

• Morning light viewing goes beyond setting one's clock.

• People who wake up late are actually hungry for light without their knowledge, which is why they come switch all these lights on at the wrong time.

The Tripartite Model

In this section, the guest introduces the tripartite model that incorporates three components: the circadian clock, homeostatic drive, and direct effect of the environment. These three components allow humans and animals to incorporate light and stress in their daily lives.

Components of the Tripartite Model

• The tripartite model consists of three components:

• Circadian clock

• Homeostatic drive

• Direct effect of the environment

• All three components must be incorporated together for humans and animals to function properly.

• Getting morning sunlight is important for entraining your circadian clock.

• Bright light during the day can help with mood regulation.

Light Viewing Behavior

This section discusses how light viewing behavior affects biological processes throughout the day.

Benefits of Light Viewing Throughout the Day

• Getting morning sunlight sets your circadian clock.

• Animals have a "light hunger" that relates to seasonal changes in food availability.

• Exposure to light in the afternoon can improve mood and sleep quality.

Drawbacks of Insufficient Light Exposure

• No specific drawbacks were mentioned in this section.

Light Viewing Behavior

In this section, Samer and Satchin discuss the best light viewing behavior for people in the afternoon/evening time. They also talk about blue blockers and their effects on vision.

Natural Light Creeping into Darkness

• The best thing to do is to let natural light creep into darkness.

• However, that would be inefficient since people want to go home, read, talk to family etc.

Extending the Day

• It's nice to extend the day.

• But it's important to block light from affecting your circadian clock.

Blue Blockers in the Evening

• Satchin personally does not like any blockers that take a single wavelength of light.

• Blue blockers prevent you from affecting your circadian clock but can distort vision because we always see in full spectrum.

Mistaken Use of Blue Blockers

• A lot of people mistakenly wear blue blockers all day long.

• People assume that viewing blue light is what was giving them headaches when it might have just been looking at screens at close distance all day.

Changing Spectrum of Light

• There are ways now where you could change the spectrum of the light and keep it white between day and night and change the content of color without affecting vision.

• Physicists know how to do this.

Intrinsically Photosensitive Circadian Setting Ganglion Cells (ipRCGs)

In this section, Samer and Satchin discuss ipRCGs and their response to blue light. They also talk about how bright lights at night can disrupt circadian cycles.

Response Best to Blue Light

• ipRCGs respond best to blue light but if the light is bright enough because they also get input from other components of the eye, it doesn't matter if you block blues.

Disrupting Circadian Cycle

• Looking at bright light at night can disrupt circadian cycles.

• Photoreceptors have a wide range of responsiveness and respond to very wide spectrum with different sensitivity.

Removing 480 Nanometers

• Just removing 480 nanometers is not going to do much since it doesn't take into account the adaptation properties of the whole retina.

• It's important to understand the system before making drastic changes.

The Importance of Light at Night

In this section, the speaker discusses the importance of light at night and how it affects our health.

Ideal Light Environment at Night

• The speaker and his wife prefer dimness at night.

• It is important to measure the minimum amount of light required to see comfortably.

• A very dim level of light is ideal for sleeping as it helps us see comfortably without inducing anxiety.

Effects of Complete Darkness

• Complete darkness induces anxiety in humans and animals.

• Red light that is very dim has a small effect on the circadian clock and does not affect sleep below 10 lux.

Importance of Educating the Public

• Educating the public about how to deal with light is crucial.

• Light is made up of many different colors, so it's important to remind people that white light is never truly white.

Adapting to Dimmer Environments

• When lowering lights, wait for 10 to 15 minutes for your system to adapt before assessing your vision.

• After adapting, you will notice that you can see quite well even with much less light.

Screens and Light Intensity

• Decrease screen intensity using programs that change screen color and intensity.

• Think about light intensity, duration, color, and time of day when considering lighting.

Snoring Issue

• One person in a meeting had a severe snoring issue.

Effects of Light on Sleep and Mood

In this section, the speaker discusses the effects of light on sleep and mood. He talks about how getting bright light in your eyes at night is something that you really want to avoid. The speaker also mentions that duration, intensity, color, and time of day are important factors to consider when it comes to light exposure.

Direct Effect of Light on Mood

• Bright light in your eyes at night is something that you really want to avoid.

• Getting bright light in your eyes at night can have a direct effect on mood.

• Duration, intensity, color, and time of day are important factors to consider when it comes to light exposure.

• It's best not to check iPhones or iPads at night.

Effects of Light Exposure on Stress and Learning

• Disrupting the timing or exposure to light can have dramatic effects on the stress system and learning/memory system.

• Light affects the circadian clock which then causes different effects.

• There is a direct effect of light independent of the circadian clock that can cause mood changes and learning deficits even without disrupting sleep or causing sleep deprivation.

• Viewing too much or too little light could make us feel happier or less happy even if we're sleeping and waking up at appropriate times.

The Perihabenular Nucleus and the Tripartite Model

In this section, the speaker discusses the brain region responsible for receiving light input for mood regulation and its connection to the perihabenular nucleus. They also introduce the tripartite model as a way to incorporate all three factors that affect sleep-wake cycles.

The Perihabenular Nucleus

• The brain region responsible for receiving light input for mood regulation is called the perihabenular nucleus.

• This region receives direct input from ipRCGs and projects to areas in the brain that regulate mood, including the ventromedial prefrontal cortex.

The Tripartite Model

• The tripartite model incorporates all three factors that affect sleep-wake cycles - circadian rhythm, homeostatic drive, and environmental input.

• It's important to get a lot of light during the day as it affects mood, learning, memory, alertness level, and homeostatic drive.

• Even if you have a good circadian and homeostatic drive, getting light at the wrong time of day or being stressed can impact your sleep.

• The same tripartite model applies to feeding where hunger and energy levels are measured by arcuate nucleus while daily intake of food depends on SCN and light-dark input. A third input exists when food is not available which depends on completely different brain regions than SCN or arcuate nucleus.

Understanding the Tripartite Model

In this section, the speakers discuss the three components of the tripartite model: circadian influence, drive to sleep, and feeding. They also talk about how light affects mood.

Components of the Tripartite Model

• The drive to sleep is extremely strong and causes tiredness around 3-4 am.

• There's a circadian rhythm that drives wakefulness in the morning.

• The perihabenular nucleus takes light and independently drives changes in mood.

Direct Effects of Light on Mood

• Seeing light early in the day sets your circadian clock.

• Getting as much bright light during the day as possible can improve your mood independently of regulating your sleep-wake cycle.

Discovering More About Perihabenular Nucleus

In this section, they discuss what is known about the perihabenular nucleus and its function.

Function of Perihabenular Nucleus

• We don't know what light does to it or how it interacts with other systems.

• There is no clear function for sleeping or why organisms have to go offline for so long.

• Lack of sleep can cause serious problems including death.

Appetite and Feeding Behavior

In this section, the speakers discuss the direct effects of light on appetite and feeding behavior. They also talk about their experiment on animals that are circadian blind but pattern sighted.

Light and Appetite

• The speakers discuss how many people are not getting enough sleep.

• They joke about arguing with each other during conversations.

• The speakers mention a paper that allowed them to come up with a tripartite model.

• This model explains how light, food, and other entraining agents interact to keep a coherent system.

Non-Light Entraining Agents

• The speakers wanted to use non-light entraining agents to train animals without light systems.

• They thought food would be the strongest non-light entraining agent.

• However, they found that light and feeding behavior actually support each other in entraining the animal's circadian rhythm.

Tripartite Model

• The tripartite model explains how different entraining agents interact to keep a coherent system for the circadian rhythm.

• Unlike vision or hearing, which are full modalities, entraining agents like light and food need to know each other's presence to work effectively.

Body as a System

• The speakers discuss how people view the body more as a system of interacting organs rather than individual parts.

• This is similar to their tripartite model for entrainment agents working together in the circadian rhythm.

Using Light to Adjust Eating Behavior

In this section, the speaker discusses how light can be used to adjust eating behavior and regulate hunger.

Importance of Regular Mealtimes

• Eating at specific times of the day signals the body's circadian clock.

• Regular mealtimes that fit the circadian clock can inform the clock and regulate hunger.

• Hunger is mainly driven by hormone cues that are timed to sleep-wake cycles and light exposure.

• The arcuate nucleus in the hypothalamus drives hunger and feeding behavior, taking cues from light exposure.

Practical Applications for Regulating Hunger

• Light exposure impacts hunger levels, making it important to regulate timing and quality of food intake.

• Timing is crucial for regulating hunger even when energy levels are not low.

• Regular mealtimes should be around a specific time with a half-hour window.

• Regulating hunger for particular phases of the circadian cycle is valuable for all people.

Overall, this section emphasizes how regular mealtimes that fit an individual's circadian clock can help regulate hunger levels. Additionally, light exposure plays a significant role in regulating hunger levels.

Eating and Mealtimes

In this section, the speakers discuss the importance of eating during active times of the circadian cycle for optimal health. They also talk about how regulating mealtimes can help with weight loss.

The Importance of Eating During Active Times

• Eating during non-active times can negatively impact health.

• Limiting eating to active times in the circadian cycle is important for overall health.

• Joe Takashi's work supports this idea.

Regulating Mealtimes for Weight Loss

• Samer regulated his mealtimes based on his circadian cycle to lose weight.

• He ate a big breakfast and lunch when he was most active and hungry.

• He avoided dinner because his circadian system shuts off at 3:00 pm.

• He regulated food intake between 12:00 pm and 3:00 pm, which was the hardest time to control hunger.

• He did not eat anything after 3:00 pm as his system shut off by then.

Samer's Experience with Eating and Mealtimes

In this section, Samer talks about his personal experience with regulating mealtimes based on his circadian cycle.

Samer's Schedule

• Samer goes to sleep at 9:00 pm and wakes up between 4:30 am and 5:00 am.

• He has a big breakfast at around 7:00 am, followed by a simple snack at around 10:00 am.

• Lunch is usually between noon to 1:00 pm, followed by another snack at around 3:00 pm.

• The hardest time for him to regulate food intake is between noon and 3:00 pm when he feels hungry all the time.

Adjusting Input of Food, Light, Clock, and Hunger

• Samer regulated his food intake based on his circadian cycle, light exposure, and hunger.

• He ate quality food and avoided eating after 3:00 pm.

• He noticed that he gained weight when he ate with enjoyment at night.

• Regulating the input of food, light, clock, and hunger helped him lose weight.

Understanding the Tripartite Model

In this section, the speakers discuss how understanding the tripartite model can help individuals understand how their sleep, feeding, and light exposure are interconnected. They also discuss how these components can affect each person differently.

Importance of Finding Optimal Times for Exercise

• Exercising at night can mess up an individual's whole system.

• Morning exercise works great for one of the speakers.

• Exercise should be done during the period in which an individual feels most alert.

Interrelation Between Sleep, Feeding, and Light Exposure

• The tripartite model should be considered to find optimal times for sleep, feeding, and light exposure.

• Light exposure controls sleep and mood and impacts feeding.

• Exercise should be done during the period in which an individual feels most alert.

• Light exposure is a complicating factor that can shift an individual's cycle if not regulated properly.

Manipulating Light Exposure to Find Optimal Times

• Manipulating light exposure is key to figuring out what works best for oneself.

• Light is the most powerful driver of sleep-wake cycles and other components discussed in the tripartite model.

• Regulating light first can help everything else fall into place.

Blunt Indicators of Doing It Right or Not

• An individual's sleep-wake cycle and exercise routine will indicate whether they are doing it right or not.

Finding Your Ideal Sleep-Wake Cycle

In this section, the speakers discuss how exercise and sleep-wake cycles are interconnected. They also talk about how different people have different ideal times for exercising and sleeping.

Exercise and Sleep-Wake Cycles

• Body temperature affects sleep, so it's important to find an exercise routine that doesn't raise your body temperature too much.

• The best time to exercise depends on when you feel comfortable in your sleep-wake cycle.

• Different people have different ideal times for exercising and sleeping. For example, a former Navy SEAL likes to train between 4:30 a.m. and 6:00 a.m., while one of the speakers prefers mid-morning workouts.

Chronotypes

• "Chronotype" is not an accurate term because it implies that sleep-wake cycles are the only factor at play. Exercise and eating habits also need to be taken into account.

• The phases of light exposure, food intake, exercise, and sleep should be coordinated in a way that makes you feel good overall.

• When these phases are aligned correctly, you will feel more energized during the day and less fatigued at night.

Personal Examples

• One of the speakers finds that getting sun exposure in the morning and early afternoon, eating mostly during the first half of the day, and exercising regularly helps him maintain his energy levels throughout the day.

• Another speaker finds that he is most productive in the morning but starts to wind down after 5:00 p.m.

Circadian Rhythms in Dogs

In this section, the speakers briefly discuss the circadian rhythms of dogs.

• One of the speakers had a bulldog with a circadian clock that slept for most of the day and was only active every third day or so.

Teenagers' Sleep Schedule

In this section, the speakers discuss whether teenagers' natural tendency to sleep in later and stay up later is due to social rhythm or biology. They also touch on the idea of morning rigor getting stronger with age.

Teenagers' Sleep Schedule

• The rumor is that teenagers naturally want to sleep in later and stay up later.

• It could be both social rhythm and biological factors that contribute to this tendency.

• Morning rigor tends to get stronger with age, which worries one of the speakers who is already a morning person.

• However, it can be nice to have quiet time early in the morning before others wake up.

Social Rhythm and Parenting

In this section, the speakers discuss how social rhythm affects parenting and how it may have evolved as a way to protect children from predation.

Social Rhythm and Parenting

• People may have different sleep-wake schedules as a way to take care of their kids throughout the day-night cycle.

• This allows for protection around early morning hours when humans are vulnerable to predation.

• The social rhythm is powerful but not as strong on the clock as people think.

• Eventually, social interactions at night can mess up one's circadian rhythm if they involve getting enough light or eating at the wrong time of day.

Staying Up Late

In this section, the speakers discuss what happens when they stay up late for various reasons.

Staying Up Late

• The speakers discuss what to do when they stay up late for various reasons, such as taking a midnight trip to the hospital or going out with friends.

• One of the speakers is known for staying up late and partying despite being an early morning person.

Effects of Circadian Rhythm on Mood and Health

In this section, the speakers discuss the impact of circadian rhythm on mood and health. They explain how prolonged periods of disrupted sleep can lead to metabolic problems, lack of exercise, and other issues.

The Impact of Disrupted Sleep

• Experiments show that it takes two weeks of a disrupted sleep schedule to cause mood disturbances.

• Even short periods of disrupted sleep can have lasting impacts on health.

• Occasional disruptions to sleep schedules are not a major concern, but chronic disruptions can lead to serious health problems.

• Accumulated problems from disrupted sleep can spiral out quickly and become difficult to reverse.

Light Exposure and Technology Use

• Light exposure is a major factor in regulating circadian rhythm.

• Dimming screens or avoiding technology use before bedtime can have a profound effect on sleep quality.

• Using sealed pouches for phones or other devices can help reduce light exposure and distractions before bed.

Personal Motivations for Studying Circadian Rhythm

• The speaker became interested in studying circadian rhythm while working in a learning and memory lab during medical school.

• The ability of organisms to measure day biologically was mind-blowing for the speaker, who had never heard about it before.

The Importance of Chronomedicine

In this section, the speaker discusses the importance of chronomedicine and getting drugs at the right time of day for optimal health.

Chronomedicine and Trackers

• Getting drugs at the right time of day is essential for our health.

• Using better trackers like Oura rings or WHOOP straps can help with this.

• However, there are even more exciting discoveries being made in chronomedicine.

Measuring Biological Components

• A single blood sample can now measure many biological components to determine where you are in the circadian clock.

• Multiple RNAs and proteins can be measured to determine what phase of the clock you are in.

• Having multiple components measured will give a better determination of your circadian phase and understanding its effect on exercise, feeding, light input, etc.

Light's Effect on Mental Health

• Humans are able to override appropriate exposure to light and light-dark cycles but suffer from things like obesity, metabolic syndromes, reproductive syndromes, endocrine syndromes, mood disorders and depressive disorders as a result.

• There is an effort to use light to improve mood and mental health through clinical trials using light to anchor people's attention and mood for focus.

• Changing spectrum of light and regulating intensities could allow people to improve their sleep-wake cycle productivity which would lead them to get more done than less.

Takeaway

Chronomedicine is an important field that has implications for our overall health by determining when we should take certain medications based on our circadian rhythms. Additionally, light exposure plays a significant role in our mental health and productivity. By understanding the effects of light on our bodies, we can improve our sleep-wake cycle and overall well-being.

Adjusting to a New Schedule

In this section, Dr. Huberman discusses how people can adjust their schedule quickly and the importance of light in regulating circadian behavior.

Using Light to Shift Your Clock

• If you get light early in the evening, it delays your clock, making you want to go to sleep later.

• To advance your clock, you should get light after the temperature low.

• You can calculate how much light shifts happen per day and adjust either in direction of delaying or advancing depending on where you are going.

Eating on Local Schedule

• Eating on the local schedule can help shift your circadian clock and avoid gastrointestinal issues when adjusting to a new schedule.

Overall, Dr. Huberman emphasizes the importance of using light as a tool for adjusting to a new schedule and provides simple strategies for doing so.

Avoiding Light When Traveling

In this section, Samer and Andrew discuss the importance of avoiding light when traveling to a new time zone. They explain how getting bright light in your eyes early in the day can be beneficial when you're at home, but it's crucial to take into account what your body thinks when you travel to a new time zone.

The Consequences of Getting Bright Light in Your Eyes Early in the Day

• It's important to avoid light when traveling because it can delay your body clock and send you to the wrong cycle.

• If you view light at 6:00 or 7:00 a.m. Italian time, for example, having just flown from New York to Italy and you didn't prepare for that trip by waking up a little bit earlier in anticipation, you are going to delay your clock.

• This delay will throw your biology back to California and cause you to be up in the middle of the Italian night. You'll be miserable.

Anecdote About Traveling Out of Phase

• Andrew shares an anecdote about traveling out of phase and falling apart mentally and physically.

• Samer advised him to go to the gym at local dawn, workout, eat, and then view sunlight starting the next day.

Importance of Aligning Your Body Clock

In this section, Samer and Andrew discuss how aligning your body clock is key for optimal focus and productivity. They share tips on how they keep their clocks aligned.

The Key Is Knowing When You're Optimal

• The key is knowing when you're optimal for focus, exercise, and other activities.

• People often feel like there's something broken inside them because they can't focus or get too sleepy in the day. But it's all subconscious.

Aligning Your Body Clock

• Samer keeps everything aligned by thinking about when he's going to be optimal for focus, exercise, and other activities.

• He never uses a timer to wake up because his system is so aligned that he wakes up naturally at the right time.

• Sometimes people wake up at 3:00 or 4:00 in the morning and can't fall back asleep. It's possible that those people were supposed to go to bed earlier.

Sleep and Seasonality

In this section, the speakers discuss sleep patterns and seasonality.

Sleep Patterns

• The amount of sleep needed varies from person to person.

• Waking up in the middle of the night is not necessarily a problem if you can go back to sleep.

• Bright light or using electronic devices before bed can affect sleep-wake rhythms and maintenance.

• Melatonin levels increase naturally at night, but can be inhibited by light exposure.

Pineal Gland Calcification

• There is no clear evidence that calcification of the pineal gland affects sleep negatively.

• The idea of pineal gland calcification affecting sleep may be an internet wellness myth.

Seasonality

• Suicides are more frequent in spring, possibly due to depression caused by lack of light during winter months.

• Humans also experience seasonal changes in eating patterns.

• Animals time their mating behavior and progeny delivery based on seasonal changes in food availability and artificial light.

Effects of Seasonality on Humans

In this section, the speakers discuss the effects of seasonality on humans and how it affects their energy levels, mood, and sleep patterns.

Seasonal Effects in Scandinavia

• People living in Scandinavia experience lower energy levels during winter months even if they don't have seasonal depression.

• During summer months, people in Scandinavia sleep less but feel more energetic.

• Lack of exposure to natural light due to artificial lighting has disrupted human seasonality.

Daylight Savings Time

• Daylight savings time disrupts human circadian rhythms and has a cumulative effect on sleep patterns and mood.

• The speakers question the need for daylight savings time and advocate for consistent lighting across seasons.

Impact of Light on Human Biology

• Light has direct effects on human biology including homeostasis, sleep patterns, and mood.

• One-hour shifts in light can have significant repercussions on human health.

The Problem with Daylight Saving Time

In this section, the speakers discuss the negative effects of daylight saving time on people's sleep rhythms and mental health.

Abolishing Daylight Saving Time

• The speakers agree that daylight saving time should be abolished in 2022.

• They believe that doing so could have a positive effect on mental health issues related to improper interactions with light.

• The circadian community has been trying for years to abolish daylight saving time, but it has been difficult to convince others of its negative effects.

Negative Effects of Daylight Saving Time

• Shifting back the clock in the fall can compound problems for late risers who need more light in the morning.

• Studies have shown that areas that are on daylight saving time all year round have higher rates of cancer and depression.

• Keeping daylight saving time consistent throughout the year is not a good solution either, as it disrupts natural seasonality and causes bumps in both spring and fall.

Individual Variation in Light Sensitivity

In this section, the speakers discuss individual variation in sensitivity to light and whether people with lighter eyes are more sensitive to light than those with darker pigmented eyes.

Light Sensitivity and Eye Color

• It makes sense that people with lighter colored eyes would be more sensitive to light because their pupils allow more light into their eyes than those with darker pigmented eyes.

Sensitivity to Light

In this section, the speakers discuss the sensitivity of individuals to light and how it can vary based on factors such as pupil size and psychological changes.

Factors Affecting Sensitivity to Light

• Pupil size can affect sensitivity to light.

• Differences in sensitivity may also be due to variations in how effective cells are at responding to light or how healthy ipRCGs are.

• Patients with bipolar disorder seem to have different sensitivities to light.

• There may be differences in sensitivity based on gender, race, and psychological state.

The Eyes and Brain

In this section, the speakers discuss the eyes' role in informing the brain about whether an individual should be alert or asleep. They also talk about genetic variations that can affect eye color and sensitivity.

The Eyes' Role in Alertness

• The eyes are two pieces of brain that inform the brain about whether an individual should be alert or asleep.

• Genetic variations can affect eye color and sensitivity based on ancestry and proximity to the equator.

Measuring Eye Sensitivity

• There is currently no way to measure ipRCG sensitivities in humans effectively.

• It is easy for optometrists to measure rod cone function but not non-subconscious measures of eye sensitivity.

• Developing techniques for measuring eye sensitivities will help determine if there are any differences between individuals based on various factors.

Sensitivity to Spicy Food

In this section, the speakers discuss whether there are any known genetic or inherited sensitivities to spicy food.

Sensitivity to Spicy Food

• There is no known genetic or inherited sensitivity to spicy food.

• Individuals can develop a tolerance for spicy food over time.

The Tripartite Model

In this section, Dr. Samer Hattar discusses the importance of changing one's relationship with light to improve health and how he plans to write a book on "The Tripartite Model."

Writing a Book

• Dr. Hattar plans to write a book on "The Tripartite Model" that puts all the components together.

• Andrew encourages him to write the book and mentions that it could be titled "Food, Mood and You."

• Regardless of what it's called, Andrew believes that Dr. Hattar should definitely write a book.

Where to Find Dr. Hattar

• Dr. Hattar's laboratory is at the National Institutes of Mental Health where he is Head of the Chronobiology Unit.

• He is active on Twitter and Instagram with the handle @SamerHattar.

• Andrew provides links for both his Twitter and Instagram accounts in the show notes.

Following Dr. Hattar

• Andrew encourages listeners to follow Dr. Hattar on Twitter and Instagram for information about chronobiology.

• He also mentions that Dr. Hattar posts pictures of incredibly spicy food on Instagram from time to time.

• Listeners can expect occasional Instagram Live sessions with Andrew and opportunities for questions and discussions about chronobiology.

Conclusion & Call-to-action

In this section, Andrew concludes his conversation with Dr. Samer Hattar by thanking him for sharing his insights on chronobiology and encouraging listeners to subscribe, leave feedback, suggest future topics or guests, check out sponsors mentioned in the podcast, support scientific research in Huberman Lab through Patreon or tax-deductible donations.

Thank You & Call-to-action

• Andrew thanks listeners for joining him in his conversation with Dr. Hattar and encourages them to subscribe to the YouTube channel, leave comments and feedback on YouTube, and suggest future topics or guests for the Huberman Lab Podcast.

• He also encourages listeners to subscribe to the podcast on Apple and Spotify, leave up to a five-star review on Apple, and check out the sponsors mentioned in the podcast as a way of supporting them.

• For those interested in supporting scientific research, Andrew provides a link where they can make tax-deductible donations at any level they like.

• Finally, he invites listeners to follow Huberman Lab on Instagram and Twitter for more neuroscience information not covered in the podcast.