Hence, when it comes to real ‘facts’ about sleep, this relative lack of empirical evidence, has, over the years led to a disproportionate amount of homespun advice, folk wisdom and old-wive’s tales.
But whilst there are many mysteries of sleep yet to be solved, the good news is, in the last few decades, science has been able to separate a lot of the fiction from the truth.
So here’s our round up of some of the scientific research behind 33 of the most commonly held myths and misconceptions about sleep.
1: Sleep is a passive activity
For a long time sleep was considered as the body’s ‘down-time’ – an absence of consciousness. But sleep is very much an active state within the body and brain.
A complex sequence of events, which follows a regular, cyclical pattern every night. Although we remain still and inactive at night, there are numerous vital homeostatic processes going on that we’re unaware of.
Some brain activities, such as delta waves actually increase when we are asleep. Also sleep is a time when the endocrine system increases production of human growth hormone and prolactin, which is vital for a healthy immune system.
And let’s not forget our dreams. Far from being an escape into fantasy land, dreaming is thought to be vital for consolidating long term memories and building neural connections.
2: Older people need less sleep
It’s a common misconception that when we get older we naturally need less sleep. Whilst it’s true that the elderly tend to experience more fractured sleep patterns, this may be a result of other health issues and the change in circadian rhythms as we age. Professor Sean Drummond of the University of California stated that:
“Older adults benefit from getting as much sleep as they get when they were in their 30s. This varies from person to person but whatever you slept when you were 35 should be the same from 75. The problem is people find it harder to sleep as they get older and they think that that is a sign that they need less sleep but that is not the case”
3:You can catch up on your sleep at the weekends
If you’ve had a busy week of work or social engagements you may have incurred some ‘sleep debt’. A common held belief is that you can catch on any hours you missed during the week by sleeping a few extra hours at the weekend.
However, some studies have shown that this may not be adequate to fully restore you for the week ahead.
Recent research has shown that whilst one long night of sleep can restore your performance back to normal levels, this effect may last as little as 6 hours after waking up.
As the day goes on your reaction times become about 10 times slower than what they were earlier in the day, increasing the risk of accidents and errors. Dr Elizabeth Klerman, a professor in the Division of Sleep Medicine at Brigham and Women’s Hospital concluded that:
“Individuals who get too little sleep during the work or school week but try to catch up on weekends may not realize that they are accumulating a chronic sleep debt.”
4: Snoring is harmless
According to the 2005 poll by the National Sleep Foundation, 32 percent of adults in America suffer from snoring at least a few nights per week. So you’d be forgiven if you thought such a common activity was relatively harmless and benign.
However, if you suffer from loud and chronic snoring, it could be a symptom of a serious, even life-threatening condition known as obstructive sleep apnea (OSA).
OSA is characterized by pauses in breathing whilst asleep which are caused by the airways becoming blocked. If left undiagnosed, OSA can reduce blood oxygen levels and put strain on the heart and respiratory systems, increasing the risk of high blood pressure, stroke and even a heart attack.
5: Sleeping pills are harmless
Sleeping pills are amongst the most commonly prescribed drugs in the world. It is estimated that up to 10% of the US population was prescribed medication for sleep disorders in 2010.
But a recent large scale study has called for doctors to rethink the way we treat people with sleep disorders. ‘Hypnotic’ medications, which include common sleeping pills such tamazepan and zolpidem, were shown to be associated with a significantly higher risk of death and cancer. The report concluded that
“Receiving hypnotic prescriptions was associated with greater than threefold increased hazards of death even when prescribed <18 pills/year.”
6: You can get by with just 4 hours sleep
Margaret Thatcher, the former Prime Minister of the UK famously remarked in an interview that she only needed around 4 hours sleep a day to function properly.
Recently, scientists discovered a gene that may explain why some people can get by with a fraction of the amount of sleep most of us need, however this is thought to apply to only around 2-3% of the population.
The rest of us need on average between 7-8 hours each night to stay fit, healthy and alert during the day. The consequences of not getting enough sleep can be very serious indeed. Sleep deprivation can cause numerous negative side effects including heart disease, depression, weight gain to name a few.
7: Watching tv helps you fall asleep
If you like watching TV before you drift off to sleep you’re not alone. In the United States watching television is by far the most popular pre-sleep activity.
Often TV is used as a sleep aid, the flickering light and constant background noise causing enough mental distraction to calm a busy mind before falling asleep.
However, research has shown that sleeping with the TV on may cause numerous health problems including depression.
Also TV emits light with a blue-ish hue. Light is the most important regulator of our biological clock, and blue light specifically is what regulates the secretion of melatonin, the sleep hormone. When exposed to blue light our body stops producing melatonin and we feel alert and awake.
8: Drinking alcohol will give you a better night’s sleep
Alcohol has a natural sedative effect so it may seem logical that a glass of wine, a whiskey or a beer before bed would help you get a good night’s rest.
Whilst it might help you fall asleep quicker, as the alcohol is metabolised through your body during the night, your sleep becomes progressively lighter and the likelihood of wakefulness actually increases.
Chronic drinkers develop a tolerance to these effects, increasing periods of light sleep, including the REM phase ,whilst reducing the amount of deep, restorative sleep.
9: Teenagers are lazy and love lying in bed
If you have a teenage child, there’s a good chance that you’ve experienced a certain unwillingness to leave the comfort of their cosy sleep haven.
A common assumption is that all teenagers are lazy, moody and unmotivated when it comes to getting out of bed in the morning. Well, research shows that there are real biological factors to explain these types of behaviour.
Starting around the time of adolescence, a change occurs in the body clock. During the years of puberty, a 2-3 hours delay occurs in the circadian rhythms and children of this age, particularly males, gradually become more ‘evening types’.
This phenomenon is known as delayed sleep phase disorder, and is characterised by a delayed sleep-wake timing. Studies have also shown that teenagers actually need around 9-10 hours of sleep as opposed to an average of 7-8 hours for most adults. However, there are many ways to help your sleepy teenager get through this biological change.
10: Daytime naps are a waste of time
In many western societies, the concept of taking a nap is viewed in a very negative light. If you’re ‘caught napping’ at work your colleagues probably think you’re a lazy so and so, and you’d be better off drinking a strong cup of coffee to perk you up.
But napping needs to be given more respect, it can improve your performance in the workplace and may even save lives.
A NASA study in 1989 showed that pilots without a rest nodded off 5 times as much as those who took a 25 minute nap during their shift. And if you still believe that naps are just for lazy people, think again, famous nappers through the ages include Einstein, Thomas Edison, John F. Kennedy and Bill Clinton.
11: Never wake up a sleepwalker
It can be quite unsettling to discover a loved one or a member of your family sleepwalking. Such nocturnal activities can range from a simple night-time stroll through to complex actions including driving or using a computer.
Although we’re beginning to understand the causes of sleepwalking, much of our current knowledge has been clouded by urban legend and fiction from books and movies.
One of the commonly held beliefs is that if you wake someone up whilst they’re sleepwalking, you’ll cause such a shock that they may suffer from a heart attack, or even die. Whilst it’s true that waking a sleepwalker may cause some distress, there is no documented evidence to prove that it can be fatal.
12: Eating turkey sends you to sleep
Have you heard about the ‘turkey coma’. This phenomenon can be observed after the meal at Christmas or Thanksgiving when relatives start falling into post-prandial slumber.
The standard explanation for this myth goes like this: Turkey contains tryptophan, a chemical used to produce serotonin, which in turn has the effect of sending us to sleep.
This urban legend is so popular it was even the premise for a whole episode of the comedy series Seinfeld.
However, turkey contains no more tryptophan than chicken, ground beef or other meats. The most likely cause of this seasonal drowsiness is a massive ingestion of protein, carbohydrates and alcohol coinciding with a natural dip in our circadian rhythms in the afternoon.
13: Everyone needs 8 hours sleep a night
Scientific studies over the years have proven that we’re not all the same when it come to the amount of sleep we need in order to function optimally the next day. Our sleep requirements also vary over our lifespan; 16 hours is normal for a new-born, whilst adolescents generally need a couple more hours than adults.
There may be a genetic link to explain why some people can thrive on less sleep, but most of us need, on average between 7 and 8 hours sleep each night.
Interestingly, there are consequences for falling outside of these norms. Sleep deprivation has been well documented as having numerous negative effects on health and well being.
However, it’s possible that oversleeping may have similar untoward effects. In one study, long sleepers were found to be more likely to have a history of depression or drug dependency, and were strongly correlated to unemployment and low soci0-economic status.
14: Night terrors are just bad dreams
Nightmares belong to a class of sleep disorder known as parasomnias, which consist of a wide range of undesirable events that occur along side sleep.
Parasomnias such as sleepwalking, bedwetting (nocturnal enuresis), teeth grinding, (bruxism) and sleep talking are relatively well known and whilst not completely benign, they’re sometimes brushed off lightly as a bit of a joke.
A much more disturbing condition known as night terrors, routinely mistaken for nightmares. Most common in children, night terrors usually occur at the start of the night, during slow-wave sleep.
Unlike nightmares, most sufferers have no recollection of the episodes in the morning. Thought to be the result of an anomalous partial awakening from slow-wave sleep, fortunately most children outgrow night terrors by the time of adolescence.
15: Early to bed, early to rise, makes a man healthy, wealthy and wise
This quote was made famous by Benjamin Franklin, scientist, polymath and one of the founding fathers of the United States. The ancient Greek philosopher Aristotle was also a fan of early morning productivity, stating ‘It is well to be up before daybreak, for such habits contribute to health, wealth, and wisdom.”
But a study at the University of Liege concluded that these great thinkers have got the facts all wrong.
When comparing larks and owls, they found that there was no noticeable difference in mental performance when the groups were tested in the morning. However, when it came to the evening, the larks performed noticeably worse at most tasks compared to their owl counterparts.
If you’re interested to find out if you’re a owl or a lark you can download a test by Surrey University here.
16: Energy drinks give you wings
Whether it’s office workers on the early morning train or students trying to get through the afternoon lectures, energy drinks are becoming more and more ubiquitous these days.
There are now over 100 types of these beverages available, all claiming to be the perfect solution for drowsiness and a general lack of energy.
But multi-million advertising campaigns cannot hide the fact that the stimulant effect these drinks produce is largely down to two ingredients, caffeine and sugar.
Whilst scientific studies have shown that certain energy drinks can indeed improve mental and physical performance, there is some doubt as to whether the effect is any different to consuming a similar amount of coffee.
It is also largely ignored that the high sugar content in some of these drinks causes a stimulating “high” that is eventually followed by a “crash.” Additionally, research into taurine, one of the ‘magic’ ingredients in Red Bull, has suggested that it could actually function more like a sedative than a stimulant.
17: Eating cheese gives you nightmares
There’s a persistent myth that eating cheese before you go to bed can cause nightmares. It’s likely that that this belief orginated in the famous book by Charles Dickens, “A Christmas Carol”.
The main protagonist, Ebenzer Scrooge is plagued by nightmares, one of which contains a ghost who asks him, “‘Why do you doubt your senses?’. In reponse, Scrooge wittily answers,
“You may be an undigested bit of beef, a blot of mustard, a crumb of cheese, a fragment of underdone potato. There’s more of gravy than of grave about you, whatever you are!”
There is however, another explanation for the myth. People who are taking a certain type of anti-depressant known as MAOI’s, have been known to have very serious, even fatal reactions when eating foods such as aged cheese ,which contains high levels of the compound tyramine.
However, a scientific link between cheese and bad dreams still evades us. James McFarlane of the MedSleep Clinic in Toronto adds”
“I think those old wives’ tales are probably partially true, but they probably relate more to overindulgence or the consumption of foods you’re not used to, which would lead to digestive problems,”
18: To cure drowsy driving, just wind down the window and turn on some music
Sleep related driving accidents are an enormous problem around the world. In 2005 a nationwide survey found that 60% of Americans said they had driven whilst feeling drowsy.
A favourite myth is that winding down your window and turning up the music will provide enough stimulus to stop you nodding off. But scientists have found that although a blast of cold air on your face will provide temporary relief from drowsiness, this may last as little as 15 minutes.
Effective remedies to combat driver fatigue, according to the study include napping, consuming coffee and somewhat controversially, nicotine.
19: Dreaming only happens during REM sleep
REM (rapid eye movement) is one of the five stages of sleep that occur every night. Discovered in 1953 by Kleitman and Aserinsky, it was observed that when patients were awoken during the REM phase the recalled their dreams most vividly.
From then on REM has always been associated with dreaming.
Although REM dreams tend to be longer, more complex and bizarre, according to a 2004 study, dreaming also occurs independently throughout non-REM sleep. Another condition in which dreaming occurs is known as the hypnagogic state.
This is the transition between wakefulness and sleep, and may involve imagery and sounds often likened to hallucinatory experiences.
20: Yawning is just a sign of tiredness
Yawning is typically thought of as an indicator of fatigue, but in reality the real causes of yawning remain a mystery even after continued scientific scrutiny.
One theory is that yawning facilitates low oxygen levels in the lungs, but this has largely been discredited after observations of foetal yawning (there’s no oxygen in the womb).
Another mystery of yawning is how contagious it can be. Studies have shown that yawning can trigger off a contagious response in up to 60% of people who are exposed. It even affects dogs!
Some scientists have proposed contagious yawning may have helped our ancestors to coordinate times of activity and rest. Another recent experiment has suggested that yawning may be an attempt to cool the brain down.
21: A warm glass of milk before bed
Some people believe that a glass of warm milk can help you fall asleep because it contains tryptophan, an essential amino acid which is responsible for producing serotonin, which is vital for healthy sleep.
However, evidence has shown that a glass of milk on it’s own will not produce these effects. You body also needs carbohydrate-rich foods which help to produce insulin.
This is essential in order for tryptophan to have any sleep inducing effects. It’s possible that the effects of milk as a sleep aid may be purely psychological. People may associated milk with their childhood, motherly care and being tucked up in bed and night.
22: Sleep disorders are difficult to treat
Sleep disorders occur for numerous reasons. They can be triggered by physiological or emotional factors and can last anywhere from a few nights to several years.
Sleep deprivation can be very debilitating and many sufferers lack the energy or motivation to explore ways of finding a solution to their problems.
Often, in desperation, people turn to sleeping pills just to get a night’s sleep, but sleep experts now recognize non-drug treatments as the most effective long-term solution to treat insomnia.
Practicing good ‘sleep hygiene‘ is the first step towards alleviating your problems. If your symptoms persist you can talk to your doctor about taking a course of cognitive behavioural therapy or CBT.
This is a package of treatments that includes stimulus control, cognitive therapy and relaxation techniques.
23: Exercise before bed helps you sleep
Regular exercise has long been promoted as a vital part of a healthy lifestyle. Common sense tells us that when we are exhausted through physical exertion we will naturally feel tired and sleepy.
So many people have come to believe that partaking in physical exercise will promote a good night’s sleep.
However, the relationship between sleep and exercise is more complicated than many people realise. The current scientific literature exploring the effects of exercise on sleep is limited and inconsistent.
One study found that total sleep time actually decreased when participants took more exercise. A different study concluded that there was no difference in the quality of sleep on non-exercise days and moderate exercise days.
Another sample of more than 2600 men and women found that 150 minutes of moderate exercise a week provided a 65 percent improvement in sleep quality.
There’s also conflicting advice as to whether you should exercise in the morning, afternoon or evening. However, don’t let the confusion put you off. The bottom line is, exercise is good for you.
If you feel it may be interfering with your sleep patterns, speak to a health professional and/or try to change your regime to see if you notice any improvement in your sleep.
24: Counting sheep helps you fall asleep
It’s an age old theory that imagining images of sheep and counting them one by one will help to lull you to sleep. However, when scientists at Oxford University ‘s Department of Experimental Psychology put this to the test they found that the opposite could be true.
Volunteers were asked to visualise a range of different scenarios as they tried to go to sleep. On average, those who pictured images of counting sheep took up to 20 minutes longer to fall asleep than those who imagined other scenarios such as a relaxing beach, for example.
The scientists concluded that counting sheep is just too repetitive and boring to occupy enough ‘cognitive space’ in the brain. Effectively this could lead to other distracting thought patterns entering your mind, making it harder for you to relax and eventually fall asleep.
25: A total ban on caffeine is necessary for insomniacs
Caffeine is the most widely consumed stimulant drug on the planet. It blocks the receptors in the brain that cause sleepiness, increasing nerve cell activity.
It also increases adrenalin and cortisol, the ‘stress hormone’, as well as boosting dopamine levels, which can lead to a slightly euphoric, ‘high’ feeling. So it’s no surprise that caffeine can seriously affect the quality of your sleep.
But before you decide to ditch that morning expresso because you’re worried about sleeping at night, bear in mind that caffeine has a half-life of around 4 – 6 hours.
This means that if you consume 200mg of caffeine at 8 am, by midday, roughly half of this amount remains in your body. Of course, the later you consume your caffeinated beverage, the more chance you’ll experience sleep disturbances.
If you have issues with caffeine dependency, it’s wise to be cautious. However, it’s not all bad news for coffee drinkers.
Research in recent years suggests that caffeine could actually help in preventing serious conditions such as Alzheimers and Parkinson’s disease.
26: Kids don’t get sleep apnea
Obstructive sleep apnea (OSA) is one of the most common sleep disorders today. A conservative estimate is that it affects 12 million Americans. OSA is characterised by breathing difficulties as the airway becomes obstructed when the sufferer goes to sleep.
The rise in obesity in recent years is thought to be one of the main reasons for the dramatic increase in cases of OSA. Over the last 10 years the number of children with sleep apnea has risen too due to the rise in obesity in both adults and young people in industrialised nations.
27: If you can’t sleep at night, stay in bed and you’ll soon drop off again
It may sound counter-intuitive but if you keep waking up at night, you may be better off getting out of your bed, rather than staying where you are, hoping you’ll drop off again.
According to Stephanie Silberman of the American Academy Of Sleep Medicine, the longer you stay in bed awake, the less you will associate your bed with a place of rest, making it even harder for you to fall asleep.
A better way to deal with sleep maintenance insomnia (frequently waking up at night) is to get out of bed and try some relaxation techniques such as deep breathing, meditation or listen to some soothing music.
28: Dreaming serves no function
Countless theories of dreaming have been put forward over the years. These include memory consolidation, wish fulfilment and ‘providing stimulation to the nervous system during development’.
Experiments have shown that rats deprived of REM sleep will die within 2-3 weeks although most of the studies on dream deprivation in humans have been less conclusive as to the importance of REM. However, it is clear that REM sleep and dreaming plays a vital part in our daily lives.
29: Natural sleep aids are risk free
Herbal sleep remedies are a very popular choice for those who are concerned about potential dangers from taking prescribed sleeping pills. However, just because something is a natural product, it doesn’t mean there are no health considerations.
For example, valerian root has been used as a sedative since Ancient Greek times, but large doses can cause dizziness and make you feel sluggish in the morning.
More seriously however, kava kava, an traditional medicine from the Pacific Islands, which has been sold as a natural sleep aid, has been reported to be a contributing factor in cases of liver and kidney failure, resulting in a warning from the U.S. Food and Drug Administration.
The bottom line is you should always try to get advice from a health professional before taking any course of medication.
30: Over the counter sleep aids are harmless
Over-the-counter (OTC) sleeping pills are widely believed to be safer than taking prescription drugs. Generally they have a low risk of complications and contain safe amounts of active ingredients, compared to prescribed drugs.
However, there are several OTC sleeping aids that contain powerful agents that, if taken in large quantities, could be equal in strength to prescription-only medications. As with any sleeping pill, OTC medications are generally best taken only for short period to avoid the risk of dependency and building up drug tolerance.
31: Sleeping less keeps you thin
It may not seem unreasonable to assume that spending less time sleeping means you will have a more active lifestyle, burning up more calories and therefore staying fitter and trimmer.
However, the latest research shows that cutting back on your sleep can actually have the opposite effect, increasing the chance that you will become overweight and even obese.
Lack of sleep suppresses our natural appetite-depressants, while fueling appetite-increasers, often leading to weight gain. A 2004 study by Stanford University found that sleep loss caused significant changes in the levels of a hormone called grehlin, which triggers appetite.
They also discovered that sleep deprivation resulted in lower levels of the hormone leptin, triggering a starvation-like response in the body. More recent studies using modern brain imaging technology have shown that sleep deprived individuals are much more likely to make poor dietary choices.
32: Sleep deprived children are always drowsy at school
When it comes to sleep deprivation, adults and children behave in very different ways. Unlike adults, who tend to become drowsy and less active when sleep deprived, many children may have the opposite reaction.
According to Dr. Jennifer Kanaan of the University of Conneticut Health Center, children who are sleep deprived tend to overcompensate for their tiredness and exhibit signs of hyper-activity, inattentiveness and impulsive behaviour.
Often these types of behaviours are misdiagnosed as attention deficit hyper-activity disorder (ADHD). A study published in the American Journal of Family Therapy in 2011 concluded that,
“children who did not have a regular bedtime had ADHD-like behaviors 8 times more frequently than children who had a regular bedtime”
33: 8 hours consolidated sleep is the norm
In recent years, segmented sleep has been the subject of a growing body of research. The historian A. Roger Ekirch has long argued that human beings throughout history have predominantly taken their sleep in two distinct chunks at night, separated by a period of wakefulness.
Medieval literature repeatedly mentions ‘first’ and ‘second’ sleep, and it is thought that even Homer, in Ancient Greek times made a reference to first sleep.
The jury is still out on deciding whether Ekirch’s research will stand the test of time, but many sleep scientists including Matthew Walker make the case that biphasic (ie two distinct ‘chunks’) sleep is a biologically hardwired trait of humans.
In his bestselling book, Why We Sleep, Walker says “all humans, irrespective of culture or geographic location, have a genetically hardwired dip in alertness that occurs in the midafternoon hours’.
Anyone that’s spent time in the Mediterranean will testify that siesta culture is a widely accepted norm – embracing not only an opportunity to escape the hottest part of the day, but also the natural circadian slump in alertness that so often occurs post-lunch.