A study has revealed that elephants sleep for two hours a day and may survive almost two days without rest.
Previously, scientists studying elephant sleep duration discovered that they rest for four to six hours every day in captivity.
However, “in their natural habitat, wild, free-ranging elephants sleep only for two hours per day, the least amount of sleep of any mammal studied to date, but this appears to be related to their large body size,” said Paul Manger from the University of Witwatersrand in South Africa.
For the study published in PLOS ONE, researchers followed two free-roaming African elephant matriarchs in Chobe National Park in Botswana for 35 days.
The elephants were fitted with an activate transmitter in their trunks to track sleep accurately and a gyroscope-based collar to monitor sleeping postures.
The researchers discovered that the elephants slept for over two hours each day, which was the shortest amount of sleep time for any mammal on land.
Elephants were observed to survive without sleep for up to 46 hours on several occasions.
The researchers discovered that the elephants were sleeping exclusively every few nights while they traveled significant distances of 30 kilometers over these periods, possibly due to predators or human interference.
“In addition, it appears that elephants only go into REM (rapid eye movement), or dreaming, sleep every three to four days, which makes elephant sleep unique,” Manger added.