Let’s face it, sleep is essential. All animals have to sleep, even though evolutionarily, it doesn’t seem like sleep is a good idea: if an animal is asleep, they can’t defend themselves, they can’t hunt for food, they can’t analyze that data they’ve been sitting on for a month (well, maybe that’s only particular to the animals in grad school). Every animal requires a different amount of sleep. For Homo sapiens (aka, you and I) the suggested time is 7-9 hours. But many people try to skimp on their sleep for various reasons, and instead we simply supplement it with copious amounts of coffee, Red Bull, or tea. However that never really seems to do the trick; it’s not an actual replacement for sleep. So why is sleep so important?
Well for starters, better sleep means better brain plasticity, or flexibility. While we sleep, our brain sorts through all the information we take in during the day, solidifying those memories and making them easier to recall. If you don’t get very much sleep, it’s more difficult to understand and remember any new information absorbed throughout the day. Recent research has found sleep may also be involved in clearing out toxic metabolic products from brain cells. The brain has a network of fluid-filled channels to clear out toxins and waste products, similar to how the lymphatic system clears out toxins and waste from the rest of the body. Lack of sleep also increases the risk for high blood pressure, seizures, depression, and overall it weakens the immune system.
Clearly given all of this information, sleep is doing some very useful things for our health. But, sleep still presents a risk for many other animals who live in environments where predators lurk around every corner. Because of this risk, animals have unsurprisingly developed quite a few adaptations to combat this risk.
So what are the best sleep adaptations?
Well, here’s five I find to be the most impressive:
Dolphins and orcas only sleep one half of their brain at a time, referred to as unihemispheric sleep. This allows these animals to keep swimming along a fixed trajectory while sleeping.
Hummingbirds have a specialized type of sleep called torpor, which is like a short hibernation. When a hummingbird sleeps, it decreases its metabolic rate to just one fifteenth of its normal rate, and their heartbeat drops from 1200 beats per minute to 50. If hummingbirds did not drop their metabolic rate when asleep, they’d have to wake frequently to eat due to their normal, insanely high metabolic rates.
Giraffes rarely sleep for longer than five minutes at a time, and they only need a total of 30 minutes a day — less than any other animal. Giraffes even sleep standing up, because they are extremely vulnerable to the large predators in their environment, such as lions, when sleeping.
Otters can sleep on land or in the sea, but when sleeping in the sea, otters often hold hands so they don’t drift apart. Otters sleeping in the sea often place themselves among strands of kelp as well so that they don’t drift with the current.
Frigatebirds are known for their extensive flight times – they can stay in the air for up to two months without touching ground. Recently, research has shown that these birds are capable of sleeping while flying – they sleep in short ten-second bursts for a total of about 45 minutes a day.
So while our stress may be interrupting our sleeping lately, at least we have the bonus of being able to sleep for more than 10 seconds at a time, and without worrying a lion may attack while we’re resting. Sweet dreams and happy brain detoxing!
Peer edited by Yogitha Chareddy