Following is a list of representative total average sleep requirements for various species in hours/day.
Brown bat 19.9, python 18.0, owl monkey 17.0, human infant 16.0, tiger 15.8, squirrel 14.9, golden hamster 14.3, lion 13.5, gerbil 13.1, rat 12.6, cat 12.1, mouse 12.1, rabbit 11.4 , jaguar 10.8 , duck 10.8 , dog 10.6, bottle-nosed dolphin 10.4, baboon 10.3, chimpanzee 9.7, guinea pig 9.4, human adolescent 9.0, human adult 8.0, pig 7.8, gray seal 6.2, goat 5.3, cow 3.9, sheep 3.8, elephant 3.5, donkey 3.1, horse 2.9 , and giraffe 1.9 hours per day.
Sleep is ubiquitous among mammals, birds, and reptiles, although sleep patterns, habits, postures, and places of sleep vary greatly.
As for human beings, we spend about one-third of our lives asleep.
Nonetheless, people generally know little about the importance of this essential activity. Sleep is not just something to fill time when a person is inactive. Sleep is a required activity, not an option. Even though the precise functions of sleep remain a mystery, sleep is important for normal motor and cognitive function. We all recognize and feel the need to sleep. After sleeping, we recognize changes that have occurred, as we feel rested and more alert. Sleep actually appears to be required for survival. Rats deprived of sleep will die within two to three weeks, a time frame similar to death due to starvation.
Sleep requirement for various species
Science correspondent - 21-07-2009 12:45 GMT-0000
A living being needs to sleep to rejuvenate itself. However, it has been debated for a long time as to how much a living being requires to sleep. After much research, biological scientists have come to the conclusion that total average sleep requirements of various species differ upto great extent - ie a brown bat needs a sleep time of almost 20 hours per day while a giraffe needs only two hours.