Scientists have just uncovered an odd and remarkable feature about elephants, one that shows just how fascinating these creatures are: they hardly sleep at all. A new study published in PLOS One found that after researchers fitted two wild African elephants in Botswana with a device to track their movements and sleeping habits over 35 days, they only slept for about a couple hours every day.

Even more interesting, they would stay awake for up to 48 hours straight if they felt threatened by either poachers or predators. Elphants in captivity sleep up to six hours a day, more comparable to humans, but the study shows that elephants may live a different lifestyle in the wild.

Scientists also determined that elephants dream every three to four days by entering what is known as Rapid Eye Movement (REM) sleep. It’s interesting that enter REM sleep so infrequently, as REM is often associated with memory retention and elephants are well known for their memory.

“Studies of sleep in captive elephants have shown that they sleep for four to six hours per day; however, the current study shows that 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,” Paul Manger from University of the Witwatersrand, South Africa, said in the statement. “In addition, it appears that elephants only go into REM, or dreaming, sleep every three to four days, which makes elephant sleep unique.”