Question: Why do some people need more sleep than others?
The long and the short of it
Our sleep question of the month comes from Penny who asks “Why do some people need more sleep than others?”
Well Penny, that is a great question. First of all, you have astutely discounted the common fallacy (propagated by grandmothers everywhere), that everyone should get 8 hours of sleep per night.
In truth, sleep need is distributed along a bell curve. On the extremes are people who need as few as 3 or as many as 11 hours of sleep each night. Eight hours (actually 7.5) is only what the average person needs.
Scientists who study this type of thing call those who need 6 hours or less “short sleepers” while “long sleepers” are defined as those who need 10 hours or more.
Thomas Edison was a famous short sleeper. He described sleep as a “waste of time”.
On the other hand, Albert Einstein reported that he did his best thinking after 10 hours of sleep.
So what do we know about these long and short sleepers? Why do some people need 10 hours and some only 5?
The answer may be in their genes.
Sleep researchers studied one family consisting of 5 “normal sleepers” and two who only needed 6 hours per night. The two short sleepers (both ladies) routinely went to bed at 10 and were up and going at 4AM. Scientists found that the two early risers had a genetic mutation not shared by the other family members. The involved mutation was on one of a family of “clock” genes that regulate our bodies’ timing mechanisms.
Actually, to call this a “mutation” is somewhat misleading. It would be more accurately referred to as an infrequent genetic “variant” that results in a “short sleeper/early riser” temperament or personality.
So, to rephrase the original question, “What is the purpose of having some people needing to sleep less and others needing to sleep more?”.
As a rule of thumb, genetic variations, such as the one between short and long sleepers, must serve some Evolutionary purpose. While no one knows what that is, here is what I like to think.
Imagine yourself as one of those ancient cave people on whom Evolution conducted its cruel survival experiments.
You wake up one morning with your eyes frozen shut and you are literally freezing to death. But, just as your life is about to slip away, the cave begins to warm and a wonderful aroma drifts by. When your eyelids finally unfreeze, you see that those two nice early riser ladies have a fire going and are cooking up a delicious rack of cave bear bacon.
So you survive one more day thanks to those two early rising ladies who share what I like to call, “the breakfast maker mutation”.
In contrast to the short sleepers, scientists have yet to identify a genetic mutation specific to those of you who can’t get by without 10 or more hours of sleep. And it is difficult to imagine that the rest of your cave family would appreciate having you snoozing in while everyone else does all the hard work of survival.
But, in fact, long sleepers have some pretty good qualities. Einstein was a long sleeper. And he turned out to be pretty useful. In fact, High School and college students who sleep longer get better grades than their short-sleeping classmates.
Another good thing about the long-sleepers is that they tend to be relatively jolly and pleasant to be around. In contrast, some groups of short sleepers have been found to be more “neurotic”—crankier, grumpier, and definitely more irritating. You know the type. Out collecting the firewood and complaining that they are the ones doing all the work (which they probably are).
I’m sure that scientists will eventually discover the “long sleeper/late-riser” gene. Until then, I think I’ll just call it “The Happy Albert” mutation.