Kittens love to rest throughout the day. Some dogs, especially older ones, enjoy snoring on the rug or sofa. And, if we stay away from domestic animals, some wild species also spend most of the day resting. Have you ever wondered why some animals sleep so much? Do they really need to rest that long?
Although numerous investigations have been carried out, the truth is that sleep (both that of people and that of other species) is one of the great mysteries of modern science. Scientists have found a relationship between sleep and the functioning of animals. For example, sleep could increase the ability of certain species to fight disease or consolidate memories. However, these associations do not accurately explain the ultimate purpose of the dream.
In addition, although sleep contributes to learning and memory, some animals do not need many hours of rest to function normally. For example, elephants are known to sleep an average of two hours, despite the fact that they are highly intelligent animals with a good memory. On the other hand, it is proven that the body of animals begins to decompose if they are continuously deprived of sleep.
The key is in diet and body size
So if sleep is so essential to animals and humans, why do some species need more sleep than others? The answer could be in the diet and body size of the animals, as a study published in the journal Nature concludes. Likewise, in much research on mammalian soil, scientists have found that less sleep is correlated with larger body sizes.
This could be because the larger an animal is, the more calories and time to feed it needs. Herbivorous animals eat low-calorie plants, so they need to eat a lot more. This could justify (in part) why elephants have evolved to survive on just two hours of sleep a day, argues David Raizen, a professor of neurology at the University of Pennsylvania School of Medicine.
However, the mystery is far from solved, since the dream is complex, difficult to measure in wild animals and, above all, difficult to interpret. Also, in the case of domestic pets, sleep could be just a matter of convenience, as they may not have anything better to do or simply cannot leave the house.
