Which animal sleeps the longest?

Koalas are famous for their sleepiness, resting or sleeping for up to around 20 to 22 hours a day. They eat eucalyptus leaves, which are low in nutrients and hard to digest, so they conserve energy by staying still for long periods. Some bats also sleep or rest for around 19 to 20 hours a day. Sloths, despite their reputation, sleep somewhat less in the wild than once thought, around 10 hours, but move so slowly they appear to be resting most of the time. Sleep patterns vary hugely across the animal kingdom depending on diet and lifestyle.