A study published in the journal Library of Science found that wild African elephants only sleep for two hours a day on average, and sometimes stay awake all day. The wild African elephant is the least sleeping mammal known at present.

Researchers from the University of the Witwatersrand and other institutions conducted a 35-day follow-up study of two middle-aged female elephants in Botswana's Chobe National Park, and found that the two elephants only slept for an average of two hours a day. Sometimes, they even "walk around" for 46 hours without sleeping, during which they walk about 30 kilometers. Researchers speculate that they may do this to avoid lions or poachers.

Wild elephants have become the least sleeping mammals known at present, which may be related to their size. The bigger a mammal is, the less likely it is to sleep.

It is observed that wild elephants have rapid eye movements during sleep every three to four days.

The scientific community generally believes that this kind of REM sleep is related to dreaming and memory consolidation, and some people think that more REM sleep time is helpful for memory.