How Animals Sleep – Fun Facts from the Animal Kingdom.
Sleeping Sea lion
Been getting enough sleep lately? Chances are, those 8 recommended hours are elusive at times, if not frequently unobtainable. The other night while I lay awake, unable to stop those chugging brain cogs, I wondered about the sleep requirements for other members of the animal kingdom. Do other animals require so much sleep? How do they sleep? Do they dream?
The next day I perused a book called, “Sleep and Rest in Animals” by Corine Lacrampe. It is not an in-depth comprehensive approach to the subject, but rather gleans some scientific results and lays it out for recreational reading. It has a beautiful collection of sleeping animal photos too. From it I gleaned some curious tidbits you may find interesting to contemplate the next time the sandman eludes you:
Birds
* Perching birds have a mechanical locking system to stabilize them when asleep. Tendons cinch toes closed and the femur connects with the pelvis to lock legs in place so they don’t fall off their perch.
* Birds, like humans, experience REM (rapid eye movement) sleep, indicating dreaming is going on. No REM sleep has been observed yet in reptiles or amphibians.
* Some birds can rest one of their two brain hemispheres at a time. Half the brain gets deep sleep and the corresponding eye is closed (the eye on the opposite side of the head), while the other half of the brain is alert to danger with an open eye.
* Of the birds studied for sleep, very short REM cycles are recorded, mostly 10-20 seconds; but many throughout the day – as much as 200 in a 24 hour period.
* Swifts are one of a few birds that can catch a few winks while on the wing. Getting 3,000-6,000 feet above a pocket of warm air, a swift flaps roughly every 4 seconds, then glides for 3 seconds as it snoozes. Penguins also have been found to sleep in brief stints while they swim during long migrations. They wake regularly to breathe at the surface.
Reptiles/Amphibians/Fish/Insects
* Crocodiles sometimes rest with open mouths for heat regulation. Vessels there are nearer the surface. Letting the sun shine in makes for faster warming if it is cool and sunny. If the croc is too hot, it allows heat to dissipate quicker.
* Sea turtles sleep, eyes closed, head rested for brief periods of time on the seabed. It must wake to come up for air.
* Outside of brumation (reptilian hibernation) it is hard to say if snakes sleep. But they sure can sit perfectly still for many hours at a time.
* Sharks sleep. Contrary to popular belief, they can lie motionless on the ocean floor for a time. Divers have even reported gently touching them without waking them.
* Tree frogs sleep. The green treefrog turns a tan color when napping.
* Insects don’t experience the same type of sleep mammals and birds do. They do however rest in various ways. The jewel wasp naps, with head folded and antenna tucked. Moths wait out the day motionless on trees, to which they may be quite camouflaged.
Mammals
* Koalas are super sleepers. They snooze about 18-20 hours per day tucked up in the branches of a tree digesting eucalyptus leaves.
* In relation to some other primates, our requirement for sleep is small. But like us, our closest relations sleep in one long stretch at night. Baboons and chimpanzees average about 10 hours of sleep; gorillas about 12 hours and orangutans get about 14 hours of sleep each night.
* Many mammals don’t sleep in one long stretch like us. The elephants’ daily cumulative sleep is about 4 hours; Giraffe, 2 hours; Okapi only 5 minutes of sleep per day.
* The dolphin sleeps for 7 hours, but like birds, only one hemisphere at a time. In this way it can keep swimming and coming to the surface to breathe while it is sleeping. Unlike birds and most mammals, no REM sleep has been detected in the dolphin.