Giraffes are known for their long necks, but did you know that their necks also affect how they sleep? For the most part, these majestic animals sleep standing up, which is a defense mechanism against predators. However, in some stages of sleep this is not possible, and the postures that giraffes adopt to cope with their unusually long necks are frankly hilarious.
Why do giraffes sleep standing up?
Giraffes are huge animals, reaching heights of 4.8-5.5 meters (16-18 feet). However, this is not enough to keep them safe from lions. One way evolution has evolved to deal with this threat is that they sleep very little and in a position that allows them to be ready to flee if necessary.
“Giraffes don’t sleep much at all, over the course of a day they sleep for about four hours,” explains Becca Keefe, giraffe keeper at ZSL London Zoo. “This sleep occurs in very short bursts lasting about five minutes. This is because giraffes are prey animals, and by sleeping for longer periods of time, they are at greater risk of attack by predators.”
When do giraffes sleep lying down?
The same can be said for horses, which, like other ungulates, mostly sleep on their feet. However, everything changes when these animals reach the rapid eye movement (REM) phase of sleep, which was thought to be characteristic only of mammals and birds but was later discovered in spiders and possibly reptiles.
“When giraffes sleep, they sleep standing up, as this is the safest way. However, sometimes they sit down to sleep,” says Keefe. “When giraffes fall into REM sleep, which only lasts about a minute, they sometimes lose the ability to support their head. During REM sleep, their head sometimes lies on its back and sometimes just rests to one side, forming an S-shaped neck.”
How do giraffes cope with a long neck during sleep?
With such a huge neck length, giraffes have to exert a lot of effort to get on and off the floor, so sleeping on the floor is limited to only one phase of sleep. That’s right, giraffes sleep using their hind limbs as pillows to hold their heads in one place as they make their way into REM sleep. This phase of sleep is critical and is thought to be important for memory consolidation and learning, so for young giraffes, such as this newborn with the bobbing head, it is an important daytime nap.
Why do giraffes have long necks?
It’s often said that giraffes’ long necks are an adaptation to reach higher into foliage than other species. However, research shows that there is a more aggressive explanation for this length.
The extinct ridiculously short giraffe Discokeryx xiezhi fought using its head as a battering ram, and these battles are thought to have strengthened the neck, creating evolutionary pressure for long necks. Today we see this in bizarre giraffe fights where males swing their heads at each other as they fight for the male.
Giraffes are amazing animals and their sleeping habits are no exception. Their long necks make it difficult for them to sleep lying down, but they have adapted to sleeping standing or sitting up. When they sink into REM sleep, they even use their hind limbs as pillows to hold their head in one place. Although the reason for the long neck is still debated, it is clear that it plays an important role in giraffe survival and behavior.
