Each new dawn on safari is met with rangers, trackers, and guests eager to start exploring and piecing together what events unfolded through the night. While we are sleeping, most animals are actually still awake. While we know that some animals are specifically nocturnal, meaning they are most active during the night, we also know that most diurnal animals aren’t sound asleep throughout the night either. So one topic that frequently comes up is how much sleep do animals actually get?
Sleep is defined as the “natural periodic suspension of consciousness during which the powers of the body are restored”.
The how’s and why’s of animals’ sleep patterns
Animals’ sleep patterns are as diverse as the animals themselves so before we answer how much sleep they get, we need to look at how and why they sleep the way they do. All mammals including humans, sleep to save their energy and restore mental and physical energy. The amount of sleep a mammal needs however varies depending on several factors including age, body size, environment, diet, and the level of safety required while asleep.
For wild animals, particularly those lower on the food chain – protection against predators is possibly the most important factor in how animals sleep and for how long. This also explains why carnivores tend to sleep for longer periods than herbivores as in addition to safety requirements, a herbivorous diet requires many hours of feeding and ruminating each day while carnivores can take in a higher number of calories in one meal.
Different types of Sleep: Monophasic vs Polyphasic
Monophasic sleepers, such as humans, generally receive their sleep in one concentrated period. We are encouraged by our circadian rhythms (a natural, internal process that regulates the sleep-wake cycle and repeats roughly every 24 hours) to sleep for extended periods at night and to be active and alert during the day.
On the other hand, polyphasic sleepers tend to sleep in multiple periods throughout a 24-hour cycle. Polyphasic sleep is therefore more common and suitable in many animals as they need to maintain some level of vigilance against predators. If threats are reduced for polyphasic sleepers, by sleeping in bigger group numbers or in safer environments (trees or termite mounds), they may feel safer and experience monophasic sleep.
How do animals sleep standing up?
Another sleeping art that some animals have mastered, in particular the giraffe and elephant, is the art of sleeping while standing. Animals that sleep while standing make use of various tendons and ligaments in their limbs to lock them in place and remain standing with minimal muscular effort. This is known as the ‘stay apparatus‘ as the legs essentially become locked and allow animals to stand and doze off for short periods.
The reason behind sleeping while standing, other than to be able to flee more readily from any nearby predators, is due to blood flow restrictions and the pressure on their internal organs that laying down for long periods would cause. This results in animals sleeping while standing up at various times during the day or night. However, these animals aren’t able to engage in rapid-eye movement (REM) sleep (the deepest phase of sleep) while standing and this is why you will from time to time find giraffes, elephants and other animals lying down to get some good rest.
Do animals dream?
The reason I mentioned REM sleep above is that this is when dreaming and memory consolidation will happen. Discussions around whether animals dream or not also often comes up and the answer is yes they do! Although different mammals spend different amounts of time in REM or non-REM sleep, as long as an animal enters the REM stage of sleep it is understood that they can dream. Bodily movements and a faster pulse and breathing are associated with REM sleep, so next time you are watching a pride of lions sleep the day away, you might notice them twitching indicating that they quite possibly are dreaming, we don’t know what about but I could imagine that it would be of their next meal. If animals that sleep standing had to enter REM sleep, they would become more vulnerable to predators and likely fall over due to the unusual bodily movements or sort of muscle paralysis that are usually accompanied by REM sleep.
Do animals like hippos sleep underwater?
Finally, I thought would include the sleeping technique that I find the most fascinating. The art of sleeping with half the brain active while the other half rests. Enabling the restorative benefits of sleep while still on the lookout for potential threats. This is known as unihemispheric sleep and has evolved to allow aquatic animals, birds, and reptiles to have the benefits of sleep, breathing, thermoregulation, and vigilance while still in the water.
Here at Londolozi, unihemispheric sleep is particularly noticeable in hippos and crocodiles as it allows them to keep surfacing for air, regulate their temperature more easily and still be aware of their surrounding to some extent. Other unihemispheric sleepers include migrating birds such as the Alpine Swift as it enables them to keep one eye open and fly for days without stopping.
Now back to the question of how much sleep animals get… well it varies significantly! But I hope you will now be able to understand the sleeping habits of your favourite animal more easily. Although as humans we struggle to function well after just one sleepless night, what we can take away from all these unique sleeping traits is that there is a minimum amount of sleep that is essential for all mammals, even for the most exceptional power nappers!