Friday, March 24, 2017
Up all night: 7 animals that hardly ever sleep
If you are a regular homo sapien you will spend a third of your life tucked up in bed, sound asleep. If you live to the respectable age of 75, then you would have successfully slept through a whopping quarter of a century. Sleep is a state of inactivity when we become less responsive to stimuli. The Oxford dictionary defines it as ‘a condition in which the nervous system is inactive, the eyes closed, the postural muscles relaxed, and consciousness practically suspended’.
We now know that, as humans, we go through five distinct stages of sleep—the first of which is light sleep where we can be woken up easily by disturbances, onto the fifth stage called ‘Rapid Eye Movement’ or REM, in which we typically dream. We also know that many mammals and birds undergo changes in the brain while sleeping just like us; reptiles also display some sleep-linked changes. In some species of flies and cockroaches prolonged sleep deprivation can also be fatal. But limited research on animal sleep, coupled with its (at best) ambiguous definition when applied across species, has meant that our information on how exactly different animals snooze is still somewhat lacking.
So just how some animals get by in life with little or no sleep at all remains something of a complete mystery to us. Here are 7 creatures able to stay up all night, nearly every night.
5. Alpine swifts
7. Orca calves