Jump to: navigation, search






This text is part of: "Science of sleep" by Piotr Wozniak (2017)

Length of sleep

  1. Myth: We should get 8 hours of sleep per night. Fact: Many people can do with less sleep and they do not need to strive at 8 hours. Others may need more than 8. We should all sleep exactly as many hours as our sleep system demands. Trying to get the prescribed 8 hours of sleep will drive some people to insomnia, while others will remain sleep deprived.
  2. Myth: People who sleep less live longer. In 2002, Dr Kripke compared the length of sleep with longevity (1982 data from a cancer risk survey). He figured out that those who sleep 6-7 hours live longer than those who sleep 8 hours and more. No wonder that a message started spreading that those who sleep less live longer. Fact: The best longevity prognosis is ensured by sleeping in compliance with one's natural body rhythm. Those who stick to their own good rhythm often sleep less because their sleep is better structured (and thus more refreshing). "Naturally sleeping" people live longer. Those who sleep against their body call, often need to clock more hours and still do not feel refreshed. Moreover, disease is often correlated with increased demand for sleep. Infectious diseases are renowned for a dramatic change in sleep patterns. When in coma, you are not likely to be adding years to your life. Correlation is not causation
  3. Myth: If you are sleepy, it means you did not get enough sleep. Fact: There are factors that are far more important for the refreshed mind than the length of sleep. The same person, depending on circumstances, can be less sleepy after a well-executed 3 hours of sleep than after a long night of poor-quality sleep. The main factors that result in daytime sleepiness are: using an alarm clock, sleeping in a wrong phase (either too early, or too late), sleep apnea, inducing sleep with sleeping pills or alcohol, and substance abuse.
  4. Myth: The body will always crave excess sleep as it craves excess food. Some people draw a parallel between our tendency to overeat with sleep. They believe that if we let the body dictate the amount of sleep, it will always ask for more than needed. As a result, they prefer to cut sleep short with alarm clock to "optimize" the amount of sleep they get. Fact: Unlike storage of fat, there seems to be little evolutionary benefit to extra sleep. Probably, our typical 6-8 hours of sleep are just enough to do all "neural housekeeping". People with sleep deficit may indeed tend to sleep obscenely long. However, once they catch up and get into the rhythm, the length of their sleep is actually likely to decrease
  5. Myth: Sleeping little makes you more competitive. Many people are so busy with their lives that they sleep only 3-4 hours per night. Moreover, they believe that sleeping little makes them more competitive. Many try to train themselves for minimum sleep. Donald Trump, in his newest book, tells you: "If you want to be a billionaire, sleep as little as possible". Fact: It is true that many geniuses slept little. Many business sharks slept even less. However, the only good formula for maximum long-term competitiveness is via maximum health and maximum creativity. If Trump sleeps 3 hours per night and enjoys his work, he is likely to run it on alertness hormones (ACTH, cortisol, adrenaline, etc.). His sleep is probably structured very well and he may extract more neural benefit per hour of sleep than an average 8-hours-per-night sleeper. Yet that should not make you try to beat yourself to action with an alarm clock. You will get shortest and maximum quality sleep only then when you perfectly hit your circadian low-time, i.e. when your body tells you "now it is time to sleep". Sleep in wrong hours, or sleep interrupted with an alarm clock is bound to undermine your intellectual performance and creativity. Occasionally, you may think that a loss on intellectual side will be counterbalanced with the gain on the action side (e.g. clinching this vital deal). Remember though, you also need to factor in the long-term health consequences. Unless, of course, you think a heart attack at 45 is a good price to pay for becoming a billionaire
  6. Myth: We can sleep 3 hours per day. Many people enviously read about Tesla's or Edison's sleeping habits and hope they could train themselves to sleep only 3 hours per day having far more time for other activities. Fact: This might work if you plan to party all the time. And if your health is not a consideration. And if your intellectual capacity is not at stake. You can sleep 3 hours and survive. However, if your aspirations go beyond that, you should rather sleep exactly as much as your body wants. That is an intelligent man's optimum. With your improved health and intellectual performance, your lifetime gains will be immense
  7. Myth: You can accumulate sleep benefit in advance. Fact: If you expect a sleepless night, it is naturally best to be in a good shape. Good sleep on a preceding night will help. However, you won't get much benefit from sleeping well in the preceding week or month. Sleep is not food. You cannot accumulate it in advance for future use. This is also why your body will not attempt to sleep longer in free running sleep. If you ever sleep inordinately long, this is only an expression of prior sleep debt. Sleep credit does not exist.


  1. Myth: Avoid naps. Fact: Naps may indeed worsen insomnia in people suffering from DSPS, esp. if taken too late in the day. Otherwise, naps are highly beneficial to intellectual performance. It is possible to take naps early in the day without affecting one's sleeping rhythm. Those naps must fall before or inside the so-called dead zone where a nap does not produce a phase response (i.e. shift in the circadian rhythm)
  2. Myth: A nap is a sign of weakness. Fact: Nap is not a sign of weakness, ill-health, laziness or lack of vigor. It is a phylogenetic remnant of a biphasic sleeping rhythm. Not all people experience a significant mid-day slump in mental performance. It may be well masked by activity, stress, contact with people, sport, etc. However, if you experience a slump around the 5th to 8th hour of your day, taking a nap can dramatically boost your performance in the second half of the day
  3. Myth: Naps reduce life expectancy. Fact: Habitual napping increases longevity. Napping may still be unhealthy in some circumstances (e.g. see Phase 11 Evening naps), however, well-timed naps are a blessing for cognition and cardiovascular health.
  4. Myth: Napping may cause diabetes. Fact: While a Chinese study found that napping was correlated with diabetes, it did not differentiate between the types of napping, or did not imply causality. Napping is often associated with sleep deprivation, which could be the primary cause of the link. Napping at wrong hours could also cause circadian disturbances, which could also be a contributing factor. Finally, pre-diabetic people nap more for health. This implies reverse causality. Well-timed naps in free running sleep should reduce the risk of diabetes, cardiovascular disorders, cognitive decline, and many other health problems.
  5. Myth: Coffee before a nap is helpful. Fact: Coffee may help you wake up from the nap fast and feel pretty refreshed. However, the freshness is likely to dissipate faster if the nap is prevented from running its natural course due to the impact of caffeine. Drink coffee before a nap only if you are in a hurry (e.g. while taking a pit stop on a long driving trip).
  6. Myth: Naps are always good. Fact: Improperly timed naps may worsen insomnia, shift the sleep phase, or result in sleep inertia. See: Best nap timing
  7. Myth: Long naps send you into deep sleep and result in sleep inertia. Fact: Indeed, naps taken too late can be very long and result in sleep inertia. However, there is nothing wrong with long naps as long as they are taken at the optimum phase (usu. around the 7th hour from natural waking). For a well-timed nap without sleep deprivation, the opposite may be true: the longer the nap, the greater the gain in alertness and learning capacity.
  8. Myth: Larks should nap at 1 pm, while owls should nap at 2:30 pm. Fact: Both larks and owls differ little in their preferred nap timing, which comes roughly 7 hours from natural waking. This means that a lark that wakes up at 4 am would feel least alert at 11-12 am, while an owl that wakes up at midday would gladly nap at 7-8 pm. Note also that natural early riser are less likely to be nappers.
  9. Myth: Everyone has his or her own optimum nap length. Fact: Optimum nap length does not exist! Naps are subject to many homeostatic regulatory inputs, and will vary in length from day to day depending on circumstances. Some people nap very predictably (e.g. always within the 15-20 min. range). Others show huge variations (e.g. from no nap to 3 hours).
  10. Myth: Power nap of 20 min. is most effective. Fact: Well-timed naps are most effective when they terminate naturally. They may last 3 min. or 3 hours. Their effect will largely be determined by the timing, napping conditions, and, importantly, lack of artificial interference in the course of the nap sleep.
  11. Myth: Don't take naps, you will only be more tired. Fact: Well-timed naps can double your productivity. Churchill noticed that a nap makes the second part of his day as valuable as the first part. If you consider that a creative mind makes more errors in a tired state when working in the evening, and errors can often wipe out effects of one's work, there is not exaggeration in the statement that naps double productivity. Naturally they must be taken correctly. Otherwise they can reduce one's performance through sleep inertia, worsen insomnia or sleep phase problems. See: Best nap timing
  12. Myth: Keep your naps at 15 min. with an alarm clock to wake up from Stage 2 NREM and avoid grogginess. Fact: Well-timed naps in a healthy circadian cycle should never leave you groggy. Just the opposite. They will offer a gift of a crisp mind for the second half of your day. See: Best nap timing. Moreover, the duration of sleep stages depends on many homeostatic control factors as well as on the circadian phase. In a sleep deprived state at a wrong circadian phase, you may hit Stage 4 in a wink. The alarm will find you stunned and disorientated.
  13. Myth: Naps should be avoided in insomniacs. Fact: Early naps, and naps in habitual nappers, have a negligible impact on the onset of night sleep. Slight delay in sleep onset comes from slightly lesser homeostatic pressure, but shorter night sleep is as refreshing as sleep in non-nappers. In most cases, insomniacs would not suffer from insomnia if they were just allowed to go to sleep later and wake up later. It is true, however, that late naps can have a disastrous impact on the sleep phase and night sleep. All naps beyond the 9 hours from natural waking should be considered late. See: Best nap timing

Sleep inertia

  1. Myth: Most people experience sleep inertia in the morning. Fact: Sleep inertia in the morning is entirely avoidable. If you throw away the alarm clock, you are not likely to experience sleep inertia (unless jetlagged for some reasons). If you need to get up at a specific hour, with some help from chronotherapy, you can either eliminate the alarm clock or make it less harmful. Morning sleep inertia hits mostly those who seriously cut down on the length of their sleep. Has mankind degraded to a degree that these people form a majority?
  2. Myth: Waking up is a slow process that needs to take its course. Fact: Waking up at the right time without the help of the alarm clock should be pretty fast. On a good day, it should take as much time to wake up as it takes to fall asleep, i.e. 3-5 minutes. There is still some improvement in the learning capacity in the first hour. However, the sleep switch has been designed so that to accomplish pretty fast awakening assuming the sleep is natural, healthy and unregulated.
  3. Myth: Excess sleep causes headaches and grogginess. Shorter sleep is better for health. Fact: This myth is yet another example of confused causation. When people catch a cold virus their thermostats shift to favor pyrogenesis (fever helps fight viruses). This means that infected people often shiver in conditions that they would otherwise find comfortable. This led to the myth that "cold contributes to catching a cold". Even the name of the virus wrongly associates it with the cold. The myth is reinforced by the fact that flus and colds rule in cold weather when people close windows and crowd in poorly ventilated spaces. Being cold is a sign of catching a cold, not a prelude to the infection. Similarly, sleep deprived people often sleep very long to repay the sleep debt. Long recovery sleep indeed often leads to headaches and other unpleasant symptoms. However, it is short sleep that caused the problem in the first place. When people are allowed to sleep as much as they want, they quickly reduce their total sleep time, and experience no "sleep excess" symptoms.
  4. Myth: Sleep inertia shows no circadian cycle. Fact: It depends on the type of sleep inertia (see: Sleep inertia). The sick groggy feeling that shows up when we are awake at the time when we should be a sleep (e.g. during a poorly planned night shift) should also be classified as a type of sleep inertia as it may show up in a very similar form independent of whether it follows interrupted sleep or a prolonged waking period. That type of inertia is purely circadian. It goes away on its own one's the circadian low passes away.
  5. Myth: Naps cause sleep inertia. Fact: Only naps taken too late cause sleep inertia. Properly timed naps taken in the absence of sleep deprivation should be relatively short (30-90 min.), and very refreshing. Sleep itself should not be blamed for sleep inertia! Sleep inertia is a result of violations in the art of good sleeping!
  6. Myth: Sleep inertia is correlated with the duration of prior sleep. Fact: You can suffer sleep inertia when being woken up from deep sleep shortly after falling asleep. You may suffer from sleep inertia when waking up from a long bout of sleep at the times of your REM peak (e.g. due to falling asleep too early). You may also feel groggy at your circadian low many hours after your last sleep episode. Sleep inertia is caused by disrupting natural sleep, NREM or REM sleep processes, and isn't much related to the length of the preceding sleep.
  7. Myth: Increasing the blood flow to the brain is a great remedy for sleep inertia. Fact: Only healthy sleep is a true remedy for sleep inertia. Caffeine, exercise, noise, bright lights, stress, etc. can only mask it. Very often, masking the inertia will do more damage than the inertia itself. For example, exercising during the subjective night is a formula for cardiac stress, injuries, and many other unhealthy effects of contradictory hormonal and metabolic signals.


  1. Myth: Silence and darkness are vital for sleep. This may be the number one advice for insomniacs: use your sleeping room for sleep only, keep it dark and quiet. Fact: Silence and darkness indeed make it easier to fall asleep. They may also help maintain sleep when it is superficial. However, they are not vital. Moreover, for millions of insomniacs, focusing on peaceful sleeping place obscures the big picture: the most important factor that makes us sleep well, assuming good health, is the adherence to one's natural circadian rhythm! People who go to sleep along their natural rhythm can often sleep well in bright sunshine. They can also show remarkable tolerance to a variety of noises (e.g. loud TV, family chatter, the outside window noise, etc.). This is all possible thanks to the sensory gating that occurs during sleep executed "in phase". Absence of sensory gating in "wrong phase" sleep can easily be demonstrated by lesser changes to AEPs (auditory evoked potentials) registered at various parts of the auditory pathway in the brain. Noises will wake you up if you fail to enter deeper stages of sleep, and this failure nearly always comes from sleeping at the wrong circadian phase (e.g. going to sleep too early). If you suffer from insomnia, focus on understanding your natural sleep rhythm. Peaceful sleeping place is secondary (except in cases of impaired sensory gating as in some elderly). Insomniacs running their daily ritual of perfect darkness, quiet, stresslessness and sheep-counting are like a stranded driver hoping for fair winds instead of looking for the nearest gas station. Even worse, if you keep your place peaceful, you run the risk of falling asleep early enough to be reawakened by the quick elimination of the homeostatic component of sleep. Learn the principles of healthy sleep that will make you sleep in all conditions. Only then focus on making your sleeping place as peaceful as possible
  2. Myth: Caffeine can cause insomnia. Fact: Caffeine can make insomnia worse but it is never a primary cause.
  3. Myth: Insomnia is caused by magnesium deficiency. Fact: There are multiple causes of insomnia. Mineral deficits do not even come close to the top of the list of causes. The most frequent causes of insomnia are stress, ill health, and sleeping in a wrong phase (too early). People on a normal healthy diet should get plenty of magnesium to meet their needs. Moreover, in cases of deficiency, insomnia would not be the main reason for worry. Various forms of diet supplementation are in vogue these days, and few people realize that supplementation may often do more harm than good.
  4. Myth: Segmented sleep is natural. This is how people slept for centuries. Fact: Segmented sleep is probably an expression of "excess nighttime". It can be observed in modern conditions when people go to sleep too early. Early bedtime is a frequent cause of nocturnal awakenings. Despite the myth, waking up in the night for longer than a few fleeting moments is not a sign of normal healthy sleep. 1-2 hour breaks in nighttime sleep are most often an indication of early bedtime or other factors that contribute to insomnia.
  5. Myth: Magnesium, folates, and other supplements can help you sleep better. Fact: Nutrients needed for good health are also good for sleep. However, supplementation is not likely to play a significant role in resolving your sleep problems. Vitamins may help if you are in deficit, but a vast majority of sleep disorders in the society come from the lack of respect or understanding of the circadian rhythm. If you are having problems with sleep, stick to the rules presented in this article. As for food, stick to a standard healthy diet. That should suffice


  1. Myth: Going to bed at the same time is good for you. Fact: Many sleep experts recommend going to sleep at the same time every day. Regular rhythm is indeed a form of chronotherapy recommended in many circadian rhythm problems. However, people with severe DSPS may simply find it impossible to go to sleep at the same time everyday. Such forced attempts will only result in a self-feeding cycle of stress and insomnia. In such cases, the struggle with one's own rhythm is simply unhealthy. Unfortunately, people suffering from DSPS are often forced into a "natural" rhythm by their professional and family obligations
  2. Myth: Sleep before midnight is more valuable. Fact: Sleep is most valuable if it comes at the time planned by your own body clock mechanisms. If you are not sleepy before midnight, forcing yourself can actually ruin your night if you wake up early
  3. Myth: It is best to wake up with the sun. Fact: You should wake up at the time when your body decides it got enough of sleep. If this happens to be midday, a curtain over the window will prevent you from being woken up by the sun. At the same time sun may help you reset your body clock and help you wake up earlier. People who wake up naturally with the sun are indeed among the healthiest creatures on the planet. However, if you do not wake up naturally before 4 am, trying to do so with the help of alarm clock will only add misery to your life
  4. Myth: Early to bed, early to rise, make a man wealthy, healthy and wise (Benjamin Franklin). Fact: Many centenarians are early risers. This adds to the impression that early risers live longer. However, early risers live long only if their early rising habit is natural. You cannot add to your longevity if you try to force yourself to an early schedule against your natural sleep habits. Everyone can be synchronized with the sun, at least for a while, and everyone can experience the beauty of getting up with the sun. Everyone should taste it at least once to know it is possible. However, for a large proportion of people this cannot last. Either due to stress, electricity, or a natural predisposition, getting up early in a natural way is not possible in the long run. When you ask a child to complete this phrase: Early to bed, early to rise, make a man wealthy, healthy and... You are more likely to hear "tired". Unfortunately, for a large portion of the population, "tired" is the correct answer. Personal development gurus will often put early rising close to the top of their productivity list. If your primary tool at work is your brain, do not follow this advice! Wake up only naturally, even if your natural wake hour is late! Natural waking is healthier, and is more likely to help you gain wisdom. Material wealth can often be gained faster if you sacrifice your health and other values, but only with good sleep will you accomplish a true wealth and well-being in life.
  5. Myth: Going to sleep early makes us more energized. Fact: Maximum morning freshness and energy comes from sleeping in the right phase. Going to sleep too early may cause insomnia or premature awakening. Both will affect the quality of sleep. For evening-type people, going to sleep relatively late will improve morning energy.

Body clock

  1. Myth: Human body clock runs a 24 hour cycle. Fact: The cycle is actually longer than 24 hours. The trick is that the brain employs a reset button that synchronizes the cycle with one's activity pattern.
  2. Myth: People are of morning or evening type. Fact: This is more of a misnomer than a myth. Evening type people, with chronotherapy, can easily be made to wake up with the sun. What people really differ in is the period of their body clock, as well as the sensitivity to and availability of stimuli that reset that rhythm (e.g. light, activity, stress, etc.). People with an unusually long natural day and low sensitivity to resetting stimuli will tend to work late and wake up late. Hence the tendency to call them "evening type". Those people do not actually prefer evenings, they simply prefer longer working days. The lifestyle affects the body clock as well. A transition from a farmer's lifestyle to a student's lifestyle will result in a slight change to the sleeping rhythm. This is why so many students feel as if they were of the evening type
  3. Myth: You cannot change the inherent period length of your body clock. Fact: With various chronotherapeutic tricks it is possible to change the period of the clock slightly. It can be reset or advanced harmlessly by means of melatonin, bright light, exercise, meal timing, etc. It can also be reset in a less healthy way: with an alarm clock. However, significant lifestyle changes may be needed to resolve severe cases of DSPS or ASPS. The therapy may be stressful, and the slightest deviation from the therapeutic regimen may result in the relapse to an undesirable rhythm. Those who employ free running sleep may take the easiest way out of the period length problem: stick to the period that is the natural outcome of your current lifestyle
  4. Myth: Human body clock can easily adapt to various types of schedule. Fact: The length of the clock period can only be changed slightly (perhaps as much as an hour). The phase of the clock can also be pushed only slightly each day (perhaps as much as 2 hours). Otherwise, all attempts to re-arrange the clock are harmful for health. Millions of people suffer due to this myth daily through badly designed shift-work, rapid time-zone changes or experiments such as Uberman sleep schedule.
  5. Myth: Night shifts are unhealthy. Fact: People working in night shifts are often forced out of work by various ailments such as a heart condition. However, it is not night shifts that are harmful. It is the constant switching of the sleep rhythm from day to night and vice versa. It would be far healthier to let night shift people develop their own regular rhythm in which they would stay awake throughout the night. It is not night wakefulness that is harmful. It is the way we force our body do things it does not want to do

Sleep in children

  1. Myth: Newborns sleep nearly all day. Fact: Newborns are more likely to spend half of their days asleep. Half of their sleep is REM (as opposed to the usual adult 20%)
  2. Myth: Babies should not play before sleep. Fact: Unless the play is exceedingly exciting or in any way stressful (even a happy play may be a form of stress), play increases the homeostatic pressure for sleep and should make it easier for a baby to fall asleep
  3. Myth: Being late for school is bad. Fact: Kids who persistently cannot wake up for school should be left alone. Their fresh mind and health are far more important. 60% of kids under 18 complain of daytime tiredness and 15% fall asleep at school (US, 1998). Parents who regularly punish their kids for being late for school should immediately consult a sleep expert as well as seek help in attenuating the psychological effects of the trauma resulting from the never ending cycle of stress, sleepiness and punishment
  4. Myth: Being late for school is a sign of laziness. Fact: If a young person suffers from DSPS, it may have perpetual problems with getting up for school in time. Those kids are often actually brighter than average and are by no means lazy. However, their optimum circadian time for intellectual work comes after the school or even late into the evening. At school they are drowsy and slow and simply waste their time. If chronotherapy does not help, parents should consider later school hours or even home-schooling
  5. Myth: Kids need to use an alarm clock to make sure they can face adversities of adult life when they will often have to get up for work early. Fact: This reasoning is analogous to letting kids smoke to make sure they can face omnipresent tobacco smoke in adulthood. Amazingly, I heard this argument from teachers who believe that school is not only a place of learning, but also a place where a kid develops its character. Sleep control system is not a muscle and you cannot train it to need less sleep. If you want to train a kid to be able to face adversity and pain, take on some healthy alternatives such as winter swimming. The only form of possible adaptation in using an alarm clock is a neural damage to the sleep control system with a possible array of sleep disorders lasting a lifetime. Sleep deprivation carries no training or educational value, and the young developing brain must be sheltered from its ravages with utmost care.

Learning and creativity

  1. Myth: Geniuses sleep little! Fact: When looking at Edison and Tesla it is easy to believe that cutting down on sleep does not seem to pose a problem in creative achievement. Those who try to work creatively in conditions of sleep deprivation will quickly discover though that fresh mind is by far more important than those 2-3 hours one can save by sleeping less. A less visible side effect of sleep deprivation is the effect on memory consolidation and creativity in the long term. Lack of sleep hampers remembering. It also prevents creative associations built during sleep. It is not true that geniuses sleep less. For example, Einstein admitted that he would work best if he got a solid nine-hour block of sleep. The difference between Edison and Einstein could be a combination of physiology and working mode. Edison would spend hours on manual experiments, which may involve less demand for sleep as compared with highly abstract reasoning. Edison also used to run his own business affairs that could add some adrenaline to affect the sleep physiology. Apart from the difference in the working mode, the sleep physiology can differ between individuals. In an extreme case, it is possible that Einstein's brain was "slower" in sleep and required more time to do the same job. His sleep could also include a larger proportion of non-optimizing stages (i.e. stages that are likely to act as transition between physiologically most important Stage 3/4 NREM and REM sleep). Whatever the underlying cause, you should follow your natural sleep demand and never cut down on sleep
  2. Myth: Sleep before learning can diminish the effects of learning. Fact: This myth comes from the fact that poorly timed sleep may result in sleep inertia, and learning in conditions of sleep inertia is particularly inefficient. However, sleep is actually the best ally of learning. Best learning occurs in the morning as long as sleep is taken in the right phase, is not disrupted, is not diminished by substances or sleep medication, etc.
  3. Myth: Since we feel rested after sleep, sleep must be for resting. Ask anyone, even a student of medicine: What is the role of sleep? Nearly everyone will tell you: Sleep is for rest. Fact: Sleep is for optimizing memories. Despite seeming inaction, the metabolic rate drops only by 15% in sleep. In an average night, that amounts to savings comparable to the energy contained in a single apple. To effectively encode memories, mammals, birds and even reptiles need to turn off the thinking and do some housekeeping in their brains. This is vital for survival. This is why the evolution produced a defense mechanism against skipping sleep. If we do not get sleep, we feel miserable. We are not actually as wasted as we feel, the damage can be quickly repaired by getting a good night sleep. It is our brain dishing punishment for not sticking to the rules of intelligent life-form: let the memory do the restructuring in its programmed time


  1. Myth: We are the least alert at 8 am in the morning. Alertness increases during the day. Fact: Alertness has two peaks during the day. For most people on a healthy sleep regimen, the alertness is highest 30-80 min. after awakening. If your alertness is low in the morning, you know you do not sleep right. Lowest alertness at 8 am might be true for people who go to sleep too late and wake up with an alarm clock. However, it is definitely not true in free running sleep. The person who got lowest alertness at 8 am would most likely keep sleeping till 10-11 am and only then wake up naturally. If you use SuperMemo and collect your sleep data, you can see clearly on your alertness graph, that alertness is highest at the beginning of the day (perhaps starting with the first hour after awakening due to the transition from sleep to wake that sometimes may take some time). Low morning alertness can only be explained by the misaligned circadian rhythm. If circadian lows occurred earlier, morning would be brisk and alert.
  2. Myth: Teenagers show stronger alerting in the evening. Fact: Teenagers have a natural difficulty in reconciling their evening activities with morning school schedules. Their lifestyle predisposes them to drift to later sleep phases and show owlish behaviors. Their evening alertness does not come from a natural difference in their circadian cycle control (as compared with adults). It comes from delayed phase shift problem that is primarily induced by their lifestyles, which are a reflection for their passion for their evening hobbies, and their high demand for sleep. When a teen cuts his or her sleep in the morning with an alarm clock, he or she is likely to take a delayed nap after school and be unusually alert in the evening. This results in late bedtime or insomnia that compounds the vicious cycle. Teens on vacation often adopt different sleep habits. See: Sleep and school

Alarm clock

  1. Myth: Alarm clock can help regulate sleep rhythm. Fact: Alarm clock can help you push your sleeping rhythm into your desired framework, but it will rarely help you accomplish a healthy sleeping rhythm. The only tried-and-true way to accomplish a healthy sleep and a healthy sleep rhythm is to go to sleep only then when you are really sleepy, and wake up naturally without external intervention

Sleeping pills

  1. Myth: Sleeping pills can help you sleep better. Fact: Sleeping pills can help you sleep, but this sleep is of far less quality than naturally induced sleep. Sleeping pills can be useful in circumstances where sleep is medically vital and cannot be achieved by other means. Otherwise, avoid sleeping pills whenever possible
  2. Myth: Melatonin can be used to boost a nap. Fact: The opposite is true. Melatonin is likely to make the nap feel very unrefreshing. Melatonin is the hormone of the night (or at least the subjective night). It can be used to advance the sleep phase or increase evening sleep propensity. It cannot be used as a sleeping pill, esp. that its effects are likely to last past the duration of a nap.

Polyphasic sleep

Myth: We can adapt to polyphasic sleep. Looking at the life of sailors, many people believe they can adopt polyphasic sleep and save many hours per day. In polyphasic sleep, you take only 4-5 short naps during the day totaling less than 4 hours. There are many "systems" differing in the arrangement of naps. There are also many young people ready to suffer the pains to see it work. Although a vast majority will drop out, a small circle of the most stubborn ones who survive a few months will perpetuate the myth with a detriment to public health.

Fact: Humans are biphasic and the attempts to modify the inbuilt circadian rhythm will result in loss of health, time, and mental capacity. A simple rule is: when sleepy, go to sleep; while asleep, continue uninterrupted.

When reading polyphasic sleep blogs, I could identify a number of myths that keep getting transmitted from blog to blog like a bad VD infection. Some even hit mainstream media:

  • False! most animals are polyphasic and so must be humans
  • False! adaptation period is hard but it ends at some point
  • False! polyphasic sleep saves you time
  • False! polyphasic naps are REM-only
  • False! you are more alert if you sleep polyphasically
  • False! you are more productive if you sleep polyphasically
  • False! you lose weight on the polyphasic sleep schedule
  • False! polyphasic sleep reduces ghrelin (the appetite hormone)
  • False! polyphasic sleep boosts testosterone levels
  • False! polyphasic sleep is healthy
  • False! long naps are bad for you
  • False! many naps are better than one nap even if you are not sleep deprived
  • False! Claudio Stampi recommends polyphasic sleep to everyone
  • False! polyphasic sleep maximizes the amount of REM an individual gets
  • False! many geniuses of history slept polyphasically. Not a single one has been documented actually

To read some hilarious extract from polyphasic sleep blogs, see: Polyphasic sleep: Myths and Facts : Excerpts from polyphasic sleep blogs