Least sleep for a mammal

The mammal that sleeps the least is the African bush (savannah) elephant Loxodonta africana, which has been found to sleep only two hours per day on average – less than any other mammal species so investigated. As revealed in their scientific paper published in 2017, research professor Paul Manger and colleagues at South Africa's University of Witwatersrand conducted a field study of sleep behaviour in this elephant species by strapping actiwatches to the trunks of two free-roaming female matriarchs in Botswana's Chobe National Park. The watches assessed their subjects' sleep/wake pattern and activity, the researchers thereby deducing that the elephants were asleep if the actiwatches showed that their trunks were still for more than five minutes. That was how the researchers ultimately revealed that wild African bush elephants, which often sleep standing up, slept in four-to-five bursts throughout the day which collectively constitute no more than two hours in total per day.

Earlier studies had shown that captive bush elephants sleep for around three-to-five hours per day. However, as captive animals do not need to be on the alert for possible predators or human hunters, and do not need to concern themselves with finding food and water as these are always made available to them by their keepers, they are able to relax more and, therefore, sleep more, secure in their safety and the knowledge that sustenance does not have to be sought.