But a definitive explanation continues to be elusive; the question remains an “unsolved mystery.”
Now an editorial by UCLA’s Jerome Siegel suggests that sleep may not fulfill a universal function across all species. Instead sleep appears to be adaptive; its role may be based on “ecological variables” that differ from one species to another.
This would explain why the sleep habits of animals are so diverse, reports the Origins Blog. For example a brown bat sleeps more than 20 hours per day; but a giraffe only sleeps for about four hours.
Siegel views sleep as “a variant of dormant states” seen in both the plant and animal kingdoms. He proposes that sleep “optimizes the timing and duration of behaviour.”
So how and when an animal sleeps is based on its waking needs. The brown bat wakes up at the time of day when its food source is most plentiful; it’s the optimal time to eat.
Why do we sleep? Perhaps we need to understand why we are awake, Siegel suggests. That may be how we find the clues to the mystery of our need for sleep.
Image by Dhyanji