Below is a list of requirements of sleep (per 24-hour period) of mammal:

Giant sloth - 20
Opossum - 19
Koala - 20
Wild lion - 16
Mouse - 13
Jaguar - 10
Chimpanzee - 9
Human,rabbit,pig,rhinoceros - 8
Gray seal,dolphin - 6
Cow,goat,donkey,sheep - 4
Horse,elephant - 3
Giraffe - 2