Photo: Wikimedia/Joeavison1
Sleep deprivation from a disturbed night? Orang-utans solve it with a nap (or two).
It is, if we’re honest, rather lovely: a quick power nap on the sofa, or heading back to bed during the day to make up for lost sleep the night before. Not to worry – an afternoon nap is by no means the exclusive preserve of toddlers and the elderly, nor even of pampered modern humans. Orang-utans, too, are fond of a daytime nap after insufficient sleep at night, as a team of German and Indonesian researchers has shown (Current Biology, 25 June).
The behavioural biologists studied the sleep patterns of 53 wild adult orang-utans in Sumatra over fourteen years. It was a challenging task – not only because of the toll it took on their own sleep, but also because orang-utans settle for the night in self-built nests high in the forest canopy. From the ground, the animals are largely invisible, so the researchers had to rely on their hearing to determine when the animals were sleeping. Orang-utans turn out to need more sleep than humans: around thirteen hours per night. It will come as little surprise that a snoring or restlessly tossing neighbour – as well as cold toes from low overnight temperatures – causes an orang-utan to sleep for less time. Longer daily travel distances also shorten the night’s sleep. To make up for this sleep deficit, the great apes nap during the day: in 41 per cent of cases at least once. For every hour less sleep at night, an orang-utan extends its siesta by five to ten minutes.
Orang-utans turn out to need more sleep than humans: around thirteen hours per night
Orang-utans are largely solitary and can therefore nap wherever and whenever they please. To do so, they build a day nest: less comfortable and elaborate than a night nest, but functional enough – perhaps comparable to a train seat or a park bench. For anyone feeling inspired: the average orang-utan nap lasts 76 minutes. Sleep well!