Elephants are the largest land mammals, but they still manage to lie down to sleep. Elephant species include the African bush elephant (Loxodonta africana) and Asiatic elephant (Elephas maximus), both of which sleep on their sides for long periods or cat nap while standing, leaning against a tree for support. Captive elephants may have different sleep patterns from elephants living in the wild. Elephants sleep in a series of naps during the night. In captivity, elephants sleep 3.1 to 6.9 hours at night, lying down for one to 4.5 hours at a time and getting up to feed between naps. Studies of wild elephants indicate they also lie down to sleep at night, for 0.67 to two hours at a time. Wild elephants may also sleep during the daytime. Bull African bush elephants have been observed taking naps about 40 minutes long between 8 a.m. and 3 p.m., according to André Ganswindt and Stefanie Münscher of the University of Pretoria, South Africa, in an article for South African National Parks.