I have been thinking about sleep this week, and how with longer days and more sunlight during summer, often we rise earlier and stay up later. This is because of serotonin released in your brain (the waking hormone) caused by sunlight (you can counter this with heavy curtains that block out most light). Melatonin is the hormone that causes sleep. Obviously these hormones work differently depending on what species you are, and whether you are diurnal, nocturnal or a crepuscular species.
Anyway – with all that technical nonsense floating around my brain I decided to share some random things about animals and sleep, with a few pictures for your enjoyment too!
Fish and snake need darkness to help them sleep due to not having eyelids – snakes may bury in substrate but fish do not, so remember to turn off tank lights
Some species of snails can sleep for as long as 3 years!
Elephants sleep only 3 and a half hours per day, usually standing
Horses and cows cannot dream unless they sleep lying down
Giraffes need less than 2 hours of sleep per day, often getting no more than half an hour of sleep daily – broken into several intervals of between 5-10 minutes – they sleep the least of of all mammals
When dogs sleep on their back, with their paws up, they are in a deep sleep
The little brown bat sleeps up to 12-20 hours a day
Cats (big & small) need a minimum of 12 hours sleep per day, on average sleep for 14 hours daily
Sharks must keep moving whilst they sleep, often covering great distances
Birds have a locking system to stabilize them whilst they sleep, perched
Dolphins and ducks can half sleep – where only half their brain is asleep at a time, the other half stays awake!
Flamingo’s also sleep half their brain at a time, whilst on one leg
Walruses can go up to 3 days without sleep, but when they do sleep they get on average of 14 hours (just like cats!) daily
Koala’s sleep approximately 18 hours daily
Sloth’s sleep 15-18 hours daily (not as much as you may have thought)
Bats sleep (and rest) hanging upside-down as their wings are not strong enough to take off from standing – they need to drop into flight
The green tree-frog turns a tan colour during sleep
Prey species tend to sleep little and often in safe (often high) places, or stood up – whereas predator species sleep for long periods and where they like