African elephants sleep for only two hours a day
After a sleepless night, they had no extra sleep the next night.
Previous studies have described elephant sleep, but many of those studies have flaws – either using captive elephants, which have different sleep schedules than wild elephants, or failing to consistently distinguish between rest and sleep, Manger said.
It also means elephants may not dream very much when they sleep. Looking to get some insight into how these lumberers slumber, the scientists from Wits teamed up with researchers from the University of California and the NGO Elephants Without Borders to monitor their sleep, by borrowing some tech from the fitness tracker world.
Measuring sleep in a controlled area, such as a lab or zoo, where the animals can be monitored at all times, is straightforward.
At an average of two hours per day, “the total sleep times recording for the two matriarch elephants in this study are substantially less than that recorded for sleep times in captive elephants and from observational studies of wild elephants”. Those two hours generally fell in the early hours before dawn and were spread out over four to five short nap sessions, like Spaniards but with more siestas. Instead, they’d walk up to 18 miles away from the disturbance, giving up a night’s sleep to avoid danger. A predator, poacher or a bull elephant loose in the neighborhood might explain the restlessness, Manger says. You also can say they nearly never sleep. Unlike females, which tend to roam in a more confined space, male elephants can traverse across country lines, making it more complicated to gather data. In contrast, the domestic horse sleeps for only three hours a day, which makes it the next shortest sleep behind that of elephants.
“It would be nice to study forest elephants, desert elephants and Indian elephants to see if their habits differ from this study”, said Manger.
“As we build up more information, the ideas for conservation will become stronger and guided by real data – and not just people’s gut feelings”, he said by phone from Johannesburg.
A four-year experiment detected the shrinking of synapses or neural connections in mice while they slept, therefore positioning sleep as a way for the brain to keep learning new things and forming new memories.
Elephants in captivity sleep for around four to six hours a day.
New research, released on Wednesday, proves that elephants are the mammals that sleep the least. According to folklore, elephants famously have the best long-term memory in the animal kindgom – yet they’re only hitting REM maybe twice a week.
Why does sleep time vary with size? Interestingly, sunlight and when the sun rises or sets did not have a profound effect on the elephants’ sleeping patterns.
Despite these drawbacks, Manger thinks the team’s results are representative. “I think what we’ve got is pretty close to the mark”, he says.
The only problem is that most studies have been done on animals in conditions of confinement.