Before revision: Comparative average sleep periods for various mammals (in captivity) over 24 hours 200px|A sleeping red fox 200px|A sleeping dog 200px|A sleeping tiger 200px|A sleeping leopard Horses – 2 hours Elephants – 3+ hours Cows – 4.0 hours Giraffes – 4.5 hours Humans – 8.0 hours Rabbits – 8.4 hours Chimpanzees – 9.7 hours Red foxes – 9.8 hours Dogs – 10.1 hours Tigers – 15.8 hours House mice – 12.5 hours Cats – 12.5 hours Lions – 13.5 hours Platypuses – 14 hours Chipmunks – 15 hours Giant armadillos – 18.1 hours Leopards – 18 hours Little brown bats – 19.9 hours Reasons given for the wide variations include the fact that mammals "that nap in hiding, like bats or rodents tend to have longer, deeper snoozes than those on constant alert."
After revision: Comparative average sleep periods for various mammals (in captivity) over 24 hours 200px|A sleeping red fox 200px|A sleeping dog 200px|A sleeping tiger 200px|A sleeping leopard Horses – 2 hours Elephants – 3+ hours Cows – 4.0 hours Giraffes – 4.5 hours Humans – 8.0 hours Rabbits – 8.4 hours Chimpanzees – 9.7 hours Red foxes – 9.8 hours Dogs – 10.1 hours hours Tigers – 15.8 House mice – 12.5 hours Cats – 12.5 hours Lions – 13.5 hours Platypuses – 14 hours Chipmunks – 15 hours Giant armadillos – 18.1 hours Leopards – 18 hours Little brown bats – 19.9 hours Reasons given for the wide variations include the fact that mammals "that nap in hiding, like bats or rodents tend to have longer, deeper snoozes than those on constant alert."