It’s no wonder there are so many myths about sleep.Modern sleep research only really began in the middle of the 20th century, with the milestone discovery of REM sleep in the 1950s.

Before that, sleep was widely regarded as a ‘passive process’ and hence, not of great interest in terms of scientific inquiry.

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.

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 fiction.

Over the last 9 days, we have been exploring some of the scientific research behind 33 of the most commonly held myths and misconceptions about sleep.

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.

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