They’re unconscious the second they close their eyes!
Location doesn’t seem to matter, or comfort, or security.
Could a champion sleeper like my husband sleep with his chin wedged between boards or draped around the wheel of a truck? I don’t think so!
Sleep needs and sleep characteristics differ quite a bit from one species to the next:
- Giraffes sleep very little– less than two hours a night–and can go for weeks without any sleep at all. Large grazing mammals with relatively slow metabolisms seem to need the least amount of sleep. Other short sleepers are horses, donkeys, and elephants.
- Small meat-eating mammals with high metabolisms need lots of sleep. At the long end of the continuum is the brown bat, that sleeps nearly 20 hours every day. Bats’ wings aren’t strong enough to propel them into flight from a standing position. So they sleep upside down, which enables them to fall into flight when they sense danger.
- Like humans, all mammals experience rapid eye movement (REM) sleep, when dreams occur. During REM sleep dogs bark and make running movements with their legs. Platypuses make movements similar to those they make when stalking and killing crustacean prey.
- Dolphins’ sleep is “unihemispheral.” While one hemisphere of the brain is asleep, the other is awake, enabling these marine mammals to swim to the surface and breathe even as they’re sleeping.
- Ducks that sleep at the end of a row, where they’re more exposed to danger, often sleep with one eye open—the eye facing outward–to better watch out for predators. Birds sleeping at the edge of a flock do the same.
- Some birds sleep on the wing. The bar-tailed godwit flies 7,200 miles from Alaska to New Zealand in eight days without touching down for refueling or sleep. The most likely explanation is that they’re able to fly with parts of their brain asleep while at the same time keeping other parts awake.
If you’ve noticed anything funny or unusual about the sleep of animals close to you, please take a minute to share it!