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We have an enormous capacity to compensate for our deficits, and we often think our behavior is normal, even when it isn't.

Preface

  • To have rhythm, to be in sync, is to be healthy, But not just any rhythm will do.
  • Living longer does not always mean living healthier
  • We have found that simply adjusting the time of how we live -- and making easy lifestyle changes is the secret to restoring our rhythm, and it will surely be the next revolution in health care.
  • Circadian comes from the Latin circa meaning "around"/"approximately" and diem meaning day.
  • Luckily it is easy to get back in sync. We can optimize our clocks in just a few days.
  • A sleep deprived brain is more dangerous than a brain under the influence of alcohol.
  • An elusive blue light sensor in the eye's retina that sends light signals to the brain clock to tell it when it is morning and when it is night.
  • To have a predictable circadian rhythm is to have healthy organs.
  • In most chronic diseases clock function is compromised.
  • Just like the first light of the morning resets our brain clock, the first bite of the morning resets all other organ clocks.
    • Mice that eat the same number of calories from the same foods within 12 hours or less everyday are completely protected from obesity, diabetes, liver and heart disease.
    • The truth about chronic disease is that there is rarely a cure.
  • This book and the method discussed is more than a diet. It is a lifestyle.
  • Most of the diseases that affect us in adulthood can be traced back to circadian disruption.

Topics

The Human Eye & The Circadian Clock

  • Human eye contains millions of rod and cone cells capturing details of images, working like a camera
  • We lose the ability to see when these rod and cone cells die.
  • Yet blind people have circadian clocks that are still influenced by light. How?
  • Many blind people can still "sense" light. Their pupils get smaller under bright light and larger when they walk back indoors.
  • There is a light sensing protein present outside the rod and cone cells that is the light sensor that sets the daily sleep-wake cycle to light.
  • This Light sensing protein is called melanopsin.
  • 1/20 retinal neural cells contains melanopsin, this protein can impact our sleep cycles, circadian clock and melatonin production.

Light & Harm to the Circadian Clock

  • Red has the longest wavelength and violet has the shortest.
  • melanopsin is highly sensitive to blue light wavelengths and less sensitive to red light.
  • When melanopsin senses blue light, brain is brought to a forced awake state and it starts thinking that it is day time.
  • Melanopsin cells barely fire up under orange light, and this results in the brain thinking it is still night! While the blue light will register as day light.
  • An hour under orange light won't disturb your circadian clock much, but an hour under blue light will exponentially disturb your clock.
  • Melanopsin takes a lot of light to activate itself. The problem here comes in the day.
  • When we stay indoors all day, dimly lit rooms cannot activate melanopsin fully, resulting in more disruptions in the circadian clock, making us feel sleepy and tired all the time.
  • A couple of days and weeks of this and you get depression and anxiety.

Our own little Master Clock

  • Every organ in an animal has its own clock, and these clocks don't need instructions from the brain in order to function.
  • Every gene in our genome has a circadian cycle. For every tissue there is a hidden time code to our genome.
  • Master clocks - a small cluster of cells that function as master clock.
  • Collectively known as suprachiasmatic nucleus or SCN, are strategically located at the hypothalamus, the center of the base of the brain.
  • The 20000 cells that make up the SCN are indirectly connected to the pituitary gland, adrenal glands (stress hormonnes), the thyroid gland, the gonads (reproductive hormones) and the pinweal gland(sleep hormone melatonin).
  • SCN's function is very central to the rhythm, such that when it is removed, (done in mice) all the other rhythms of the animals were lost.
  • SCN s the link between light and timing. It shares the information received from the outside world about light to the rest of the body.

Sleep & Waking

  • Sleep is the beginning of our biological day, not the end.
  • Sleeping
    • While we sleep, our brain is busy consolidating memories and creating new connections between different neurons.
    • HGH (Human Growth Hormone) is produced when we sleep. A lack of sleep can reduce the amount of hormone and hinder growth in children and adults.
    • The brain detoxifies. Toxins created in the day, in the brain are cleaned and filtered out during a night's sleep.
  • When do You go to sleep?
    • The most accurate answer would be, the time when you have shut off the lights, checked your last email/text etc, and are in bed with your eyes closed.
  • Waking Up
    • When daylight lengthens as we approach summer, our internal clock wakes us up at a slightly earlier time in the morning.
    • Interestingly, your evening activities have a large effect on your circadian rhythm.
    • Even before you wake up, your internal clock starts working by starting to shut down the production of the sleep hormone melatonin from our pineal gland.
    • Our breathing becomes slightly faster and our heartbeat picks up a few beats per minute.
    • Our core body temperature notches up half a degree even before we open our eyes.
    • Our entire sense of health is guided by our daily rhythms.
  • Sleeping less
    • Results in working more under bright lights, especially at night. The brain doesn't expect to be stimulated at this hour.
    • We are not programmed to sleep less as we get older. With age, we become more sensitive to different factors that affect us, but we still need the same amount of sleep.
  • While Awake
    • Staying Indoor, not getting sunlight exposure. This confuses the brain clock.
  • When and How to wake up!
    • First ray of light entering your eyes activates melanopsin light senors in your retina that tells your SCN master clock that morning has arrived.
    • If you need a real alarm clock to wake up, your SCN is not ready and still thinks it is night.
    • The goal is to be less reliant on the alarm clock and to get enough hours of sleep that you wake up naturally.
  • Three Stages of Sleep
    • N1 (drowsiness), N2(light sleep), N3(Deep sleep)
    • The three stages of quiet sleep above alternate with periods of active sleep (REM).
    • First REM episode lasts for a few minutes, and REM time increases progressively over the course of night.
    • You get your best sleep in the first 4 hours of your sleep, you get some of your best sleep here, ideally between 10pm to 2am. This is because you pay your sleep debt here.
    • When you nap in the day time, you can rarely sleep for more than 2 to 3 hours, your circadian code simply won't allow it.
  • Sleep Debt
    • The difference between the amount of sleep you should be getting and the amount you actually get.
    • It increases our propensity to sleep, while circadian rhythm instructs us when we should sleep.
    • A week of reduced sleep can raise someone's blood glucose to prediabetic levels.
  • Fragmented sleep
    • Waking up more than once during the night for at least a few minutes, to the point where it is difficult for you to go back to sleep.
    • The brain registers only the time you sleep, and it responds as if it is not getting any sleep at all during the periods of fragmented sleep.
    • Moreover, it takes additional time to get back to that deep sleep phase and you miss out on this continuous uninterrupted sleep.
    • Main Causes of Fragmented Sleep are dehydration, too hot/cold temperature, acid reflux (eating too late in the evening), sleeping with a pet, snoring/sleep apnea, other noise.
  • Snoring
    • Adults may snore when we put on some extra fat or when our muscle becomes weak around the breathing canal.
    • Our wind pipe gets obstructed when we are asleep and that leads to snoring.
    • Mouth breathing reduces the amount of oxygen that goes into the brain. Putting the brain in a hypoxic or low-oxygen state. This increases the chance of getting dementia and various brain-related problems like memory loss.
  • Stopping Snoring
    • Using a gentle saline spray or neti pot. These are meant for cleaning and opening up stuffy noses.
    • Saline spray is safe for both adults and children to use everyday.
    • Using a sleeping aid that keeps your nose open
      • One that pulls the skin on your nose open, a 'Breathe Right nasal strip'
      • Inserted inside your nose to open the airway.
    • One aspect of you feeling tired is that your brain is not getting enough oxygen during the daytime.
    • Snoring still continues after the above fixes? See an ear, nose and throat specialist or a pulmonary medicine specialist.
  • Sleep Apnea
    • A blockage or obstruction in the nasal cavity or throat or floppy tongue that obstructs your airways either partially or completely during the night.
    • The obstructions deprive the brain and the body of oxygen and cause an automatic response that wakes you up just enough so that you breathe again, although you may not wake to the point of consciousness.
    • This can happen all night long, resulting in a very less or complete lack of N3 (Deep Sleep) stage.
    • Some people with sleep apnea tend to snore, but not all of them.
    • People with sleep apnea have a higher blood pressure that might lead to higher risk of heart disease and stroke.
  • Sleep Medications?
    • While effective, sleep medicines have never been tested for continuous use for longer than 6 months.
    • Sleep medications are not a permanent cure for sleep problems. If you use them and get accustomed to them, your brain starts relying on the medication to help you fall asleep.
    • If you really think you need sleep medications, try a high-quality melatonin supplement first.
  • Melatonin Supplements
    • Taking melatonin supplements 2 to 3 hours before going to bed will make you fall asleep quicker.
    • But beware, melatonin can interfere with blood glucose regulation.
    • Taking melatonin after a meal slows down the decline in blood glucose to the normal level. It is a bad idea to take melatonin right after eating, wait atleast an hour or two so that melatonin does not interfere with your blood glucose level.
    • If you are planning to go to bed around 10pm, take your dinner at 6pm and your melatonin at 8pm.
  • Behavioral Techniques for Better Sleep
    • Don't look at your watch/clock/phone when you cannot get to sleep or wake up in the middle of the night.
    • Don't create stress around bedtime or worry that you will wake up late the next day. Use alarm for office and works but aim at waking without one everyday.
    • Don't create stress about your last night's sleep and worry that you will have the same bad experience again.
    • Don't fret over the hours of sleep you are currently getting.
    • Don't use bedroom for anything other than sleep. It's not a study or a living room or a home theatre.
  • Towards a better sleep
    • A good idea would be to reduce the temperature in your bedroom to 21 degrees or lower so that your skin feels cooler.
    • Take a shower or warm water bath just before going to bed. Warm water forces blood flow toward the skin and away from the core.
    • Triple pane glass in your window will cut the sound out significantly. Earplugs while travelling to dim down the noise.
  • Poor Sleep
    • leads to poor performance
    • When sleep deprived, your performance is worse than someone who has had two alcoholic drinks (williamson et. al. 2000)
    • Sleeping less results in us doing something else more, exposure to more light at night, or to more food during the day or the night.
    • All of the above mentioned options will result in a disrupted circadian rhythm.
    • Waking up with a join pain may be a sign that you did not get adequate sleep for several days in a row.
    • People who sleep less tend to eat more calories, and more junk to fuel the few extra hours of wakefulness.
    • A sleep deprived brain or one exposed to bright light at night craves excessive calories that it does not need.
  • How to Sleep then?
    • Best way to improve sleep is increase the drive to sleep and avoid the factors that suppress or disrupt sleep in the first place.
    • The Drive to Sleep:
      • Increases every hour we are awake. (want to go to bed early, wake up early.)
      • Exercise/Physical activity under the sun o under diffuse daylight.
      • Caffeine reduces our sleep drive and keeps us awake (Reduce caffeine after midday.)
  • The best ways to wake up
    • By going to bed early.
    • Getting bright light immediately after waking up (sunlight)
    • A quick 5 to 15 minute walk. Exercise. Anything in bright daylight.
    • Be consistent and wake up at the same time everyday.
      • If you are waking up 2 hours late on weekends, it is a sign that you are not getting enough sleep on the weekdays.

Food

  • The quality of your food matters significantly when it comes to your health.
  • But it is not limited to how much we eat and what we eat but also when we eat that matters. Especially for long term positive health outcomes.
  • Why cook food? Why not eat it raw?
    • It tenderizes food, breaks down strong flavors and makes food safer by killing pathogens.
    • Makes food more digestible, allowing more calorie digestion from the same ingredients.
  • Food Processing and preservation techniques, along with refrigeration, made it possible to have access to food all the time. And that's when the trouble really began.
  • Your First Bite of the Day
    • It does not matter whether it is a cup of coffee or a whole bowl of cereal, when you break the fast note the time. Your eating window has begun.
  • Your Last Bite of the Day
    • Write down when you took your last bit or last sip (other than medication or water) of the day.
  • Only 10% of the adults eat for 12 hours or less on a consistent basis.
  • People eating their food withing 8 to 11 hour window will reap the most benefits out of this program.
  • Compare your last bite/sip time with your bedtime. The difference should ideally be 3 hours or more.
  • People eating the same calories, same food with different eating time periods, consistently for a period of time have shown different results.
  • Eating with an 8hour time period being the ideal eating window helping you tap into the wisdom of our circadian rhythm of body and brain.
  • Following this for a few weeks would give you tons of benefits such as
    • Restoring hormonal balance, immune system, mood, sleep, happiness and libido.
  • Ghrelin and Leptin
    • Ghrelin - produced whenever stomach is empty. Hunger hormone. Signals brain that you are hungry
    • Leptin - produced in fat cells. Signals brain that you are full.
  • Children given dinner at the same time and put to sleep early in the evening every night were far less likely tot develop obesity by age 11.(Anderson et al. 2017)

Time Restricted Eating (TRE)

  • Mice that follow an eating window of 8-9 hours sleep better.
  • They don't sleep longer than other mice, but get more deep sleep.
  • TRE improves sleep by increasing the arousal threshold.
  • Mice eating TRE didn't gain excess gain excess weight and they had normal bloodnt de sugar and cholesterol levels
  • Mice on a 15 hour diet were not very healthy as compared to those who ate for 8,9,10 or 12 hours remained healthy.
  • Individuals who spread their calories over a longer period of time didn't lose as much weight as the people who consumed same calories from same food in a shorter window.
  • When you eat is more important than what you eat. But this doesn't give you a free pass to eat anything in your eating window.
  • Observed Benefits of TRE:ObservedBenefitsOfTRE.png
  • Starting TRE
    • Start by establishing an 12 hour eating window for a week or two
    • Then try to decrease the time you eat by an hour a week.
  • The optimum eating window is between 8 to 11 hours.
  • The health benefits you get at 12 hours double at 11, and continue doubling till 8 hours.
  • Eating for less than 8 hours a day is not sustainable for long term as there is a limit to how much you can eat at a time.
  • TRE is not about counting calories, but about being responsible about when you eat.
  • How does this work?
    • Most of your body's fat burning happens 6 to 8 hours after finishing your last meal and increases almost exponentially after a full 12 hours of fasting.
  • A Typical TRE Day
    • Setting an ideal time for breakfast. The moment you eat breakfast or have your first cup of coffee or tea is the beginning of your eating window.
    • If breakfast begins at 8am dinner must end by 8pm for a 12 hour window.
    • It's healthiest to eat breakfast as early as possible as the insulin response is better in the first half of the day and worse in late night.
    • That is, more carbs can be broken in the morning more efficiently as compared to night. It is however always recommended to eat a low carb breakfast.
    • Finishing your meals before melatonin begins to rise at dawn(evening) is important to escape the effect of melatonin on blood sugar.
    • Melatonin reduces the ability of pancreatic beta cells to secrete insulin. Without insulin glucose stays in the bloodstream and this is the reason why your body is less efficient at breaking carbs in the evening.
    • In the morning you might be hungrier, it's okay to eat more provided you are eating healthy food.
    • Recommendation: Eating protein earlier in the day triggers the right amount of acid secretion in the stomach.
      • Instead of having more acid at night following a protein rich dinner, aim for getting most of your protein requirement with the breakfast itself.
      • This will reduce occurrence of heartburn and give you a better sleep. Pasted image 20250527093746.png
    • Carbs consumed at dinner will end up being stored as body fat as body's glucose control is weaker at night.
  • Dinner Drinking
    • If you plan to have any alcoholic beverage, have it before or with dinner, not after.
    • Your body needs a lot of water, especially when working in a dry environment like an air conditioned office building.
    • Don't count coffee as a water source as coffee is diuretic which will make you dehydrated and suppress sleep due too its caffeine content.
  • Snacking is okay during day but not at night
    • Try to push past your late night hunger swings by drinking a glass of water; as your body adjusts to the new rhythm we are setting.
  • Maintain your weekly routine on the weekends
    • When you change your eating window on different days. Your metabolic clock is automatically affected, as if you had traveled between two time zones within a week.
    • Eating late at night is by far the worst choice you can make, and it will totally defeat any benefits you've achieved throughout the day.
  • FAQs and IMP points
    • TRE is a lifestyle**; not a temporary try once get benefits diet thingy.
    • When choosing your 8 to 12 hour window time, it is recommended to choose early in the day as later in the day means poor carbs->blood sugar handling due to higher melatonin presence.
    • TRE can be combined with other diets such as high protein keto diet.
    • If you feel light headed or dizzy after 12 hours of not eating, stop TRE and talk with your physician
  • 7 Foods to stay away from
    • soda, diet or otherwise.
    • prepackaged fruit juices or vegetable juices. (preservatives can corrode your intestinal lining)
    • breakfast cereals. (You don't have to start/end your day with sugar)
    • "Energy", Protein, fruit-and-nut bars. They're just candy bars. (preservatives and sugar yikes)
    • Processed food that contains corn syrup, fructose or sucrose. (Your body doesn't recognize them as forms of sugar; they trick your system to think there is no sugar in blood causing your blood sugar levels to rise up. Very dangerous if you are prediabetic or have diabetes.)
    • No dark/hot chocolate in the evening(High caffeine content). Milk chocolate instead has half the caffeine as dark chocolate, eat it right after lunch though.
    • Commercially processed nut butters. Added sugars, oils, preservatives.
  • If you feel you need a protein drink, choose one without sugar.
  • Complex Carbohydrates - the better alternatives
    • healthiest carbs are found in non starchy, leafy, green vegetables and fruits and grains that are low on the glycemic index (GI).
    • Glycemic Index (GI) ranks carbohydrates from 0 to 100 based on how quickly they raise your blood sugar after eating.
    • High-GI carbohydrates spike your blood sugar, causing a flood of insulin that triggers your body to store fat and become hungry.
      • Good for pre/post workout meals
      • Bad for regular meals, fat loss and managing hunger.
    • Slow burning, lower GI foods e.g. oatmeal and green vegetables, citrus fruits and berries cut your appetite.
    • Foods higher in fiber are predominantly carbs but they are good choices because your body can't digest fiber and it scrubs your intestines as it leaves the system.
    • Fiber helps detox your body and provides nutrients for a healthy gut.
    • Basmati Rice is High GI; switch to parboiled rice instead. Harder to digest since it is a complex carbohydrate.
  • Good Sources of Healthy Fats
    • You need dietary fat for brain development and to keep your skin and hair healthy.
    • Fat helps to absorb micronutrients including vitamins A, B, D, E and K.
    • Healthiest fats are those that are found in whole foods.
    • Saturated fat is not unhealthy or fattening, despite what you might have been told.
    • Monounsaturated fatty acids are the best fats and are liquid or soft at room temperature.
      • Found in olive oil, avocado, nuts, seeds and egg yolks.
    • Polyunsaturated fatty acids found in plant and animal foods are also a good source of fat.
      • Omega 3 -- maintaining good health, control and reduce body fat (omega 3 has the ability to increase blood flow -> fats delivered more easily to sites where metabolism is stimulated.)
      • Omega 3 found naturally in few plant foods (e.g. flax), fish, salmon, shrimp, some eggs.
      • Omega 6 -- found in highest quantities in vegetable oils (corn, soy, safflower), polyunsaturated fat found in chicken, beef, pork.
      • Your body cannot make these fats by itself, thus these are essential fats.
    • Refer following food chart for Low GI foods, protein foods, nonveg, veg and seeds along with healthy fats and oils.
    • Low-Glycemic Fruits and Vegetables
      • lowGIFruitsAndVeggies.png
      • Protein SourcesPasted image 20250531094828.png
      • Healthy Alternatives to staplesPasted image 20250531094857.png
  • More benefits
    • Maintain a 12 hour TRE or more, you will find nutritious foods taste better
    • Your taste buds and sense of smell are now better sensitized, meaning they are now highly activated.
    • A clearly defined eating period also revives your hormone production and puts it back in its natural synchrony.
    • Increases the level of an enzyme that breaks down cholesterol in the liver.
    • It is not just about weight loss: It is a method for addressing real health concerns.

The Circadian Clock

We Are all Shift Workers
  • 1 late night of partying can be just as disruptive as travelling from one time zone to another. That's why we call it social jet lag.
  • Roughly 87% of adults have social jet lag and go to bed at lease 2 hours later on the weekend.
  • A brain on shift work cannot make rational decisions.
  • A single night shift has cognitive effects that can last a week.
  • A few days of reduced sleep can change out appetite, both for the kinds of foods we crave and how much we want to eat when we stay awake at night.
  • Children of shift workers had more cognitive, behavioral problems and higher incidence of obesity
  • WHO for Cancer has classified shift work as potential carcinogen.
  • Who is a shift worker?
    • A person who stays awake for more than 3 hours between 10.00 pm and 5.00 am for more than 50 days in a year fits the official European definition of shift worker.
  • Digital Jet lag: This happens when you chat with friends or colleagues are several time zones away.
    • At night, plants leaves can drop, because it would be a waste of energy to keep the laves raised.

  • Circadian rhythm is not exactly 24 hours; even the time of the day is not precisely 24 hours.

  • The brain is primed for learning and problem solving in the first half of the day.

  • In the afternoon, we feel healthy if we have accomplished enough work to feel satisfied with our efforts.

    • Pasted image 20250531095035.png

  • Vitamin D has nothing to do with our clock.

  • Our clock is influenced by light! Yes, the light that goes through our eyes.

The Three Core Rhythms

  1. Sleep
  2. Nutrition
  3. Activity
  4. All the clocks in different organs work in harmony to create the above three rhythms.
  5. When we work against our optimal rhythm, it confuses the signals and eventually compromises our health.
  6. After 12 hours of being awake, our brain clock gently nudges us to begin preparing for sleep.
  7. A major way to improve your circadian code is by correcting habitual behaviors.

Food, Liver and Digestion

  • The liver, is an exception. The food resets the clock here, not the brain. This is groundbreaking!
  • An erratic breakfast confuses your organs and compromises their function
  • The same food that would have taken a couple of hours to digest at 6pm takes longer to digest at 8pm because you are now outside the 10 hour optimal eating window.
  • Our cells cannot make and break up body fat at the same time.

  • Every time we eat the fat making program turns on and the cells in our liver and muscles create some fat and store it.

  • But, what is the big deal? It's just a few hundred grams of fat gain from late night snacks right?

  • But it is worse that than. Worse than what you think.
  • It is hard enough for our body already to maintain and monitor all the hormones, genes and clocks for someone with a strict eating routine.
  • But, when eating occurs at random times throughout the day and night, the fat making process stays on all the time.
  • Just set an eating routine and stick to it. Timing is everything.
  • Food and Productivity
    • Eating more food doesn't mean brain will function better
    • The brain actually works better on an empty stomach
    • Your performance during the day is primarily determined by what you did the night before -- when you ate and how much you slept.
    • Both modest fasting and exercising have a similar brain-boosting effect.
    • Each of the above two can increase a chemical called brain-derived neurotropic factor (BDNF) that improves the connection between brain cells and improves brain function.
    • Having plenty of BDNF with a good night's sleep, your brain is better prepared for performing complex tasks, staying focused and being productive.
    • Eating a late night meal negatively affects your ability to pay attention the next day.
  • Coffee Productivity myth
    • Although coffee can improve alertness, it does not remove sleep debt.
    • Coffee does work as a quick fix to hack your sleepiness but it's not an ideal choice for optimal health.
    • If you feel sleepy after a big lunch, and need a cup of coffee to stay awake, you might want to shift your big daytime meal to the morning and have a lighter lunch that will make you feel less tired.
  • Lack of Sleep and the Circadian Code for Learning
    • Lack of sufficient sleep doesn't give our brain enough time to consolidate memories.
    • Staying up late reduces brain function and productivity that night
    • The following morning, as we wake up late and rush to work, we have little time to get the right amount of morning light exposure that will brighten our mood.

Exercise & Circadian Code

  • Research has found that mice that exercised had a better circadian code, better sleep quality at more appropriate time and were less sleepy when they were meant to be awake.
  • Even among older adults, moderate physical activity ensures fewer episodes of feeling sleepy during the day.
  • Syncing your exercise to your circadian code
    • Exercise's mood-boosting effect is critical to keeping you calm and integral to productivity.
  • Your Minimum dose of Exercise
    • Anyone healthy enough to exercise should exercise for at least 150 minutes in a week or 75 minutes of vigorous exercise, or a combination of both.
    • Pasted image 20250531095108.png
    • The above 'Relative energy expenditure' of various physical activities are described in Metabolic Equivalent of Task (MET) metric
  • Get moving, exercise - When we don't use our muscles, we lose muscle mass and at the same time build up body fat.
  • Exercise and the Circadian Rhythm
    • After exercise, cells inside our muscles produce several molecules.
      • interleukin-15(IL-15) -- known to increase bone mass, better deeper sleep.
      • irisin -- reduced amounts correlate with obstructive sleep apnea.
    • exercise increases the level of an enzyme involved in the production of heme - the pigment in our blood carrying oxygen to all tissues.
  • To maintain the healthiest bones we need to have a strong sleep-wake cycle, eat at the right times and exercise.
  • Two types of muscles
    • Slow twitch - rich in mitochondria and help us perform endurance exercise e.g. marathon running
    • fast twitch - less mitochondria and help us when sprinting.
  • Having a better circadian clock appears to increase slow-twitch muscles. (Schroder et al.)
  • When to Exercise
    • If you have fasted for 10 ti 12 hours before your morning walk, run or bike ride, you will likely tap into your stored body fat for energy during your exercise.
    • If you start morning activity before breaking your overnight fast, your muscles will spend more energy, using even more fat as the energy source, literally melting away even more body fat.
    • The more muscle you have, the more calories you'll burn throughout the day and the leaner and healthier you will be.
  • Exercise in the morning
    • Improves mood for the day, stimulates new brain cell production and your ability to make new neuronal connections for deeper learning and more memory.
    • Helps repair damaged brain cells by improving neurons ability to repair their own DNA.
    • Exercising in cold air imparts additional benefits such as activation of brown fat or conversion of white to beige fat. Brown fats have more mitochondria, more mitochondria means more fat to burn.
    • You can simply burn fat by being exposed to cold temperature.
  • Exercises in late Afternoon
    • Starting from 3.00pm to dinnertime, muscle tone begins to rise, this is the best time for strength training, or vigorous exercise like intense cycling.
    • Studies have shown that motor coordination and strength peaks around late afternoon.
    • Exercise is known to reduce appetite, afternoon exercise can help reduce hunger at dinnertime.
    • Exercise helps our muscles take up more glucose in a mechanism that does not depend on insulin (Ritcher et al. #todo read about this).
      • As little as 15 minutes of exercise boosts our muscles' ability to absorb some blood glucose and keep it in healthy range.
    • The positive benefits of exercise outweigh a lost hour or two of TRE.
  • Exercise after Dinner
    • Late night exercise can increase cortisol to morning levels and delay the rise of melatonin and sleep.
  • Night-shift workers and exercise
    • Nighttime exercise can increase alertness and suppress sleep.
      • Can be used to the advantage of night-shift workers
    • Avoid coffee and use high-intensity exercises so that you get good sleep once your shift is over.
  • Wolverine Diet of Hugh Jackman is actually an 8 hour TRE diet.
  • Combining TRE with endurance sports gives our body double the benefits.
  • Exercise reduces your hunger hormone ghrelin and increases satiety hormones.

Shift Work

  • One night of shift work can throw off your cognitive abilities for an entire week.
  • Our circadian clock takes almost 1 day to adjust to each hour of time zone shifting. For some people upto 2 days per hour of shift!
  • Similarly, when you delay sleeping by 3 hours because of a social event, or eat breakfast 3 hours late, you affect your cycle the same way as the jet lag affects it! This is called as Social Jetlag.
  • A change to any of the three core rhythms -- sleep, timing of food and activity -- can affect any of our organs in a similar way.
  • Remember, when one rhythm goes done so does the rest!
  • What is common, is not always normal.

  • Most people have different rhythms on weekends and weekdays.

  • Once you start knowing your code

    • Sleeping on time without using devices for 2 hours before bed
    • Not eating post sunset, ideally outside your 8-12 hour eating window.
    • Exercising at same time every day
  • You might still end up sticking to your current lifestyle that you think is unavoidable for job and/or family, which may lead to slowly succumbing to chronic diseases.
  • Or, you can make the decision that your health is more important to you and your family!

The Epigenetic Code

  • Our existing habits and environments are another layer of information that affect our DNA.
  • It is so powerful that once the habits are enforced it becomes very hard to escape them.

Optimizing Learning and Working

  • 7 Criteria for learning
    1. Attention
    2. Working Memory
    3. Positive/Negative Reward Assessment
    4. Hippocampal Memory
    5. Alertness
    6. Mood
    7. Autonomic Function
  • Attention
    • The ability to stay focused and complete a task without distraction.
    • Without paying attention, we cannot create memories.
    • We are more internally driven to be attentive during the day and are naturally prone to being less attentive at night.
    • Sleep deprivation messes with your attention.
  • Working Memory
    • The ability to absorb information, retain it and connect it to information you have already learned.
  • Positive/Negative Reward Assessment
    • If you have slept well and you're hungry you are more likely to make the positive reward choice and buy an apple or banana.
    • A sleepy brain is more likely to make poor dietary decisions.
    • Without good sleep we are likely to say something we will regret.
      • Sleep deprivation affects our relationships in similar ways.
  • Hippocampal Memory
    • Hippocampus, part of the limbic system of the brain, playes an important role in consolidation of information from short-term memory to long term memory.
    • A major function of sleep is memory consolidation in the hippocampus.
      • You are more likely to learn and remember a new language, a new math chapter or play a new video game better if you have had sufficient sleep.
    • Long-term memory suffers with sleep deprivation.
  • Alertness
    • As the day goes, the circadian clock instructs your brain to be less alert.
    • As melatonin goes up stress hormones and alertness go down. That's why less attentiveness in the night.
  • Mood
    • Our state of mind - happy, energetic, low, anxious, irritable, angry, etc.
    • Having less sleep disrupts a normal response to events and makes us susceptible to more extreme mood swings.
    • One of the natural factors that most influences mood is light.
      • A day in a dark room -- foggy mind and low mood
    • Insufficient light triggers depression-like mood and impairs learning (in mice according to study done at Johns Hopkins uni.)
      • This happens because of insufficient activation of blue light sensor, melanopsin.
    • Office workers with access to daylight had better mood, performance and sleep quality than those working in windowless offices.
  • Autonomic Function
    • Brain is composed of a central nervous system (where all active learning takes place), a peripheral nervous system (connects the brain to organs to control movement) and an autonomic nervous system (controls everything that happens automatically).
    • Chronic sleep deprivation or an interrupted sleep routine can increase the level of stress hormones produced or sensitize our stress system such that we automatically overreact in response to minor stressors (Meerlo et al.).
    • Many hormones and bacteria found in the gut can affect brain function and mood causing panic attacks or anxiety if the master circadian clock is broken.
    • TRE improves daily rhythm in the brain's autonomic functions so that the right amount of stress hormones are produced, which then improves mood.
  • THE Optimal Workday
    • With above 7 factors at their peak, you ability to get work and learning done is high.
    • Your optimal brain function is between 10am and 3pm.
      • We are in the right frame of mind during this window for making good decisions, solving multifaceted problems and navigating complicated social situations.
    • The rising phase of peak performance starts at 10.00am.
    • during these hours, your brain is really performing at its peak: your attention, working memory, assessments, and mood are at their highest levels.
    • From noon onwards, your brain begins to slow down.
    • tired in the afternoon?
      • Maybe you are dehydrated (Ganio et al. - Mild dehydration impairs cognitive performance and mood of men)
      • Working in a windowless office or doing monotonous tasks can also cause fatigue.
  • Work day beliefs and suggestions
    • Give up the notion that staying up more hours will make you more productive.
    • During day, optimize productivity with natural light exposure to keep you more alert and productive.
    • Our circadian rhythms are designed to adapt to natural cycle of light and darkness. Use that to your advantage.
    • When you wake up bright light is detected through the eye's blue light sensor melanopsin, melanopsin then tells the brain to stop producing sleep hormone melatonin and start increasing the production of the stress hormmone cortisol which makes you alert and ready for the day.
    • One way to access more daylight is by having breakfast by a window or having breakfast outside.
    • While ideal to have daylight in the morning, having some outdoor time anytime of the day is better than none.
    • When indoors choose to sit next to the largest window available. On a good day you might get 2000 to 5000 lux of light but if you move 6 feet away from the window, the light may only be measured at 500 lux.
    • We want to boost light when awake and reduce light (blue spectrum significantly) during the night.
    • If you have to work late into the night, hack your light.
    • You'll be more productive if you switch to task lighting (lighting that lights up only your work area are reduces direct exposure to your eyes, as compared with overhead or horizontal lighting)
    • Don't let your work disrupt your sleep schedule. There is no way you can be productive and tired at the same time.

The Ultimate Disrupters: Light and Screens

  • Light exposure at night may be linked to heart disease, metabolic disease, reproductive issues, gastrointestinal disease, immunological disease, etc.
  • Interestingly these are the same diseases that we have seen rise in the past few decades.
  • Some people still might be less sensitive and have no trouble falling asleep in under usual light in a living room.
  • Others might find that the same level of light keeps them awake late into the night and that they can sleep only in a darkened bedroom.
  • different types of light that are Rich or poor sources of blue light Pasted image 20250531095208.png
  • What to do with Lights then?
    • Install dimmer switches on current LED lights - In the day lights go on at full blast, at night they can be dimmed down to just enough level to allow safe movement.
    • Install different light bulbs in different rooms, one for night use one for day use if you have two.
    • Motion activated path lighting that shines directly on the floor.
    • Task lighting instead of flooding the room with light.
  • If you wear prescription eyeglasses, ideally you should not coat the glasses you wear during the day with blue light filter because you still need blue light during the day time.
    • It will make your jet lag worse if you are travelling.
  • Continuous use of blue light filtering glasses during the day essentially filters out most of the blue light we badly need to maintain mood and entrain the circadian clock to the local time.
  • For people with iphone -- myLuxRecorder is an app that you can use to find the level of luminescence (light present in the room).

The Clock, Microbiome and digestive concerns

  • By tweaking your lifestyle and paying more attention to your circadian code, you can restore your health.
  • Daytime saliva secretion neutralizes stomach acid that may come up through our esophagus into our mouth.
  • When we eat and food enters the intestine, it does not move by itself. The food is squeezed along by the digestive tract by muscles that surround the tube.
    • This is called gut motility or gut contractility
  • Eating a heavy meal and lying down immediately afterward does not allow food to move down the intestinal tract as fast as it should, and this also leads to acid reflux.
  • Short sleep duration is associated with a high ghrelin level and ultimately, obesity.
  • When travelling to a new time zone, eating at a time appropriate to the new time zone is the best way to reset the gut clock.
  • Preservatives are added to inhibit the growth of bacteria that spoil food. When these get into our intestines, even at low concentrations they inhibit the growth of gut bacteria affecting the composition of the gut microbiome.
  • Metabolism - The chemical reactions that occur in the body to use nutrients we eat to produce energy, make the building blocks to repair and grow cells, and eliminate waste.
    • As we keep on snacking our body remains in fat-making mode and cannot break down fat.
    • Only after 6 to 7 hours of not eating does our body begin to start burning some fat.
  • TRE is a better method of eating because you are training your body to adapt to your natural circadian code rather than an artificial schedule.
  • Brain produces more melanin at night, which in turn reduces insulin secretion by pancreas at night.
    • Now, if we snack late at night, the low insulin drip is insufficient to instruct the liver and muscles to bring additional glucose inside their cells.
    • This leaves the blood glucose levels dangerously high causing further damage.

Treating Cancer with TRE?

  • Shift workers have been shown to have fragile immune system
  • Most common threat inside a cell is oxidative stress
    • Oxidative stress occurs as a direct result of additional oxygen molecules entering the cell.
    • It leads to chronic and systemic inflammation
  • After eating, when every cell uses nutrition to make energy, they produce reactive oxygen species.
    • The cellular clock is responsible for sending in antioxidant defense mechanisms to coordinate with the building oxidative stress.
  • Autophagy
    • controlled digestion of bits and pieces of a cell
    • lysosome - contains acids that are capable of digesting cell's stray bits and pieces.
    • One the cellular garbage is digested, the raw materials remaining are used to build new cellular parts.
    • TRE is known to increase the autophagy for a few hours during the fasting period.
    • Autophagy is more active several hours after our last meal and then slows down when we eat.
  • Circadian Disruption
    • Makes tissue of brain cells stressed -> Stressed cells produce many chemicals activating tissue immune cells, leading to chronic inflammation in the brain -> depression, multiple sclerosis, schizophrenia, etc.
  • Having a strong Circadian Rhythm helps you recover faster during a hospital stay because it improves tissue repair, reduces inflammation, helps regenerate damaged tissue, and minimizes stress on your body.
  • TRE improves every cell's immune defense system.
    • Cells produce more antioxidants that neutralize free radicals when we follow TRE, so less cellular damage is incurred.
    • Improves autophagy, more damage is removed and recycled.

Brain Health

  • It's more likely that genetic and environmental factors interact to produce disease.
  • Maintaining a circadian rhythm builds resilience against these brain diseases.
  • Adult brains have special stem cells, producing new neurons throughout our lifetime.
  • adult neurogenesis - the process of replacing damaged/dead neurons with new neurons.
  • If any of the brain's circadian clocks are disrupted, the neurons associated with it can become easily stressed, damaged, or die off, or the process that cleans up the mess can be affected, causing more stress and damage.
  • Indoor lighting can have profound effect on our circadian code, especially when we are sick.
  • Being under daylight is getting a free dose of a brain lifting vitamin.
  • Having more daylight also makes your sleep more resilient against the evening light and sleep delaying.
  • The comparisons are being made with mice in the book and this summary because mice have a genome (DNA) sequence very similar to humans; meaning what works for mice is most likely to work for us humans as well.