In this Special Feature we hack into some of the myths surrounding the duration of sleep. We ‘re asking, among other questions, whether anyone can really get by on five hours of sleep every night. We also uncover whether deprivation of sleep can be fatal.
Although we are all aware that sleep is vital to maintaining good health, many unanswered questions still remain. And a number of theories and half-truths have grown and persisted over the centuries.
This section is the second and last part of our series tackling myths related to sleep.
This time we ‘re focusing on myths surrounding how much average person needs to sleep. We also talk about naps, the effects of sleeping too little or too long and sleep in the kingdom of animals.
1. Everyone needs 8 hours
Like in other facets of human physiology, the approach to sleep is not one-size-fits-all. Overall, research suggests that 7–9 hours is an appropriate amount for healthy young adults and normal-sleeping adults.
However the story becomes a little more complicated. The amount of sleep we need every day varies over our entire lives:
- newborns need 14–17 hours
- infants need 12–15 hours
- toddlers need 11–14 hours
- preschoolers need 10–13 hours
- school-aged children need 9–11 hours
- teenagers need 8–10 hours
- adults need 7–9 hours
- older adults need 7–8 hours
You can train your body to need less sleep
There’s a widespread rumor you can train your body to need less than 7–9 hours of sleep. Unfortunately that’s a myth.
It’s unusual for someone to require less than 6 hours’ sleep to work, according to experts. While some people may tend to feel good with a minimal sleep, scientists suggest that they are more likely to be accustomed to the negative effects of decreased sleep.
Those who sleep for 6 hours or less each night get used to the effects of sleep deprivation, but that doesn’t mean their body wants any less sleep. Cynthia LaJambe, a sleep specialist at the Transportation Institute of Pennsylvania in Wingate, explains:
“Many people believe they are adjusting to be more awake, but in reality they are operating at a lower stage. We don’t know it because it happens so slowly that the functional decay.
“In the end, there is no denying the effects of sleep deprivation. And training the body to sleep less is not a viable option.”
– Cynthia LaJambe
Nevertheless, it is worth remembering that with less than 6.5 hours of sleep each night, certain rare individuals do seem to work perfectly. There is proof that this may be due to a rare genetic disorder, and one will not be able to train themselves to do that.
2. Daytime naps are unhealthy
Experts usually advise people to skip naps to ensure a better night’s sleep. However, a tactical nap can help repay some of the accrued sleep debt if someone has missed out on sleep during the previous nights.
A good nap period is about 20 minutes. It provides enough room for the body to recover. People who sleep much longer than this could mean they go down into a deep sleep, and they feel groggy once they are awake.
Daytime napping in the United States is relatively common but in some countries taking a “siesta” is the norm. Of course, during the early afternoon our bodies tend to dip in energy, so maybe napping around that time is more natural than avoiding sleep until nighttime.
After all, the vast majority of mammals are polyphasic sleepers, meaning they will sleep all day long for short periods of time.
In a broad review of the effects of napping, the authors explain afternoon naps in people who are not deprived of sleep can lead to “subjective and behavioral improvements” and improvements in “mood and subjective levels of sleepiness and fatigue.” They found people who nap experience improved performance in tasks such as “addition, logical reasoning, reaction time, and recognition of symbols.”
But not all naps are equal. There is a lot of variation, like the time of day, duration, and naps frequency. One author explains:
“Epidemiological studies suggest a decrease in the risk of cardiovascular and cognitive dysfunction by the practice of taking short naps several times a week.”
The author also recognizes the need for even more work to clarify how napping-related factors affect health outcomes.
It is also important to note that if an individual experiences severe tiredness during the day, such as sleep apnea, this may be a sign of a sleep disorder.
Researchers will need to do more work before they can actually put all the theories and misconceptions of napping to rest.
3. All animals sleep
Since we are sleeping and our family animals seem to be sleeping, many people believe that all animals are doing the same. This is not real. A paper authors titled “Do all the animals sleep? “Ellipse:
“Certain animals never exhibit a state that meets the definition of sleep behavior. Others suspend or greatly reduce the ‘sleep’ behavior during the postpartum period or during seasonal migrations for many weeks without any consequent ‘sleep debt.'”
We further clarify that it does not appear that all marine mammals, reptiles, fish, and insects join REM sleep.
Since sleep is not only a lack of consciousness, but a rhythmic cycle with distinct neural patterns, it is a challenge to determine whether an animal sleeps or takes a rest.
“[F]ewer than 50 of the nearly 60,000 vertebrate species have been tested for all of the criteria that define sleep, ” the authors explain. “Of those, some at any time of their lives do not meet the sleep criteria, and others appear to be able to greatly reduce or go sleepless for long periods of time.”
4. More sleep is always better
Although many people are struggling to get the amount of sleep they need to feel refreshed, some are sleeping longer regularly than their body needs. One might think this could bestow superpowers on these individuals.
Researchers however establish a correlation between longer periods of sleep and poorer health. One study , for example, which followed 276 adults during 6 years, concluded:
“The risk of developing obesity has been elevated for sleepers of short and long duration compared to sleepers of average duration, with risk increases of 27% and 21 % , respectively.”
This result took hold even when the scientists monitored the body mass index measurement for age , sex and baseline. According to some studies, the sleep period may also affect mortality.
A meta-analysis that appears in the journal Sleep, states that “in prospective population studies, both the short and long duration of sleep are significant predictors of death.”
5. Sleep deprivation can be lethal
No record of anyone dying of sleep deprivation is available. This may be feasible in principle, but it is unlikely so far as scientists can tell.
Yet why this myth could have taken hold is understandable. Like many people can attest, sleep deprivation can feel terrifying. Randy Gardner ‘s experience however indicates that extreme lack of sleep is not fatal.
He was a part of a sleep deprivation experiment in 1965, when Gardner was only 16. In all, he remained awake for 11 days and 24 minutes, which is equivalent to 264.4 hours.
During this time fellow students and sleep scientists closely watched him. Sleep deprivation symptoms worsened as the days rolled on but he survived. And why did this misconception persist?
A research from the 1980s may have its origins in the idea that sleep deprivation would kill. Rechtschaffen and colleagues found they would die after 2–3 weeks if they deprived rats of sleep using a particular experimental method.
The researchers had placed rats on a disc suspended above water in their experiments. They monitored their brain activity continuously. The disc would automatically move if the animal fell asleep, and the rat would need to behave to avoid dropping into the water.
Given the fatalities in the experiments at Rechtschaffen, subsequent studies found that this is not the norm. Rats deprived of sleep, will not die using various methods. Certain researchers who used the pigeon disc test have noticed it wasn’t fatal to these animals.
Sleep deprivation is not, however, painless to humans. Gardner’s parents were concerned about their son back in 1965. They asked United States Lieutenant Commander John J. Ross. He was studied by Navy Medical Neuropsychiatric Research Unit in San Diego. He describes a perpetual deterioration of function.
On day 2, for example, Gardner found it harder to concentrate his eyes. He was unable to focus by day 4, and was irritable and uncooperative. He also recorded his first hallucination and grandiose illusion on day 4.
On day 6 Gardner ‘s speech was slower, and as his memory deteriorated by day 7, he began slurring. On day 10, Paranoia set in, and on day 11, his facial expression and voice tone were expressionless. His concentration and memory span had diminished significantly.
He did not die though, and clearly had no long-term health issues.
One explanation why the misconception continues that sleep loss can be deadly may be due to a disorder called deadly family insomnia. Individuals with this unusual genetic condition will find themselves unable to sleep. Furthermore, when people with this condition die it is due to the neurodegeneration that affects them rather than lack of sleep.
Although sleep deprivation probably won’t kill you directly, a note of caution should be added: being overtired increases the risk of accidents. “Drowsy driving kills-it claimed 795 lives in 2017,” according to the National Highway Traffic Safety Administration.
Likewise, a study published in 2013 suggests that “[a]roughly 13 percent of work-related injuries could be attributed to sleep problems.” Therefore, although sleep deprivation is not specifically lethal, it can have fatal consequences.
Additionally, if we constantly deprive our bodies of sleep for months or years, the risk of developing several conditions, including cardiovascular disease , hypertension, obesity , type 2 diabetes, and some forms of cancer, will increase.
All in all, every night we should try and aim for 7–9 hours’ sleep. It sounds simple but it is more difficult than we might want in our neon-lit, busy, and noisy lives. Everything we can do is continue to make an effort to give sleep the space it deserves.
It is only through ongoing research that we will finally unravel all the mysteries of sleep.