Every person has their own sleep habits. Animals too. And as with people, the differences are telling.
Herd animals and predators
Herd animals such as zebras and wild horses sleep briefly, in power naps. They must be able to flee quickly. Predators such as lions sleep up to 20 hours a day, resting by day, hunting by night. Life gives them no other way.
Elephants and bears
Elephants and giraffes sleep the least: about 4 hours. Bears the most: up to 8 months.
Cats and dolphins
Cats spend 70% of their life asleep. Dolphins never sleep fully, always one brain half awake, 8 hours a day.
Bats, panthers, cows
Bats hang upside down. Panthers choose a high branch. Cows can sleep standing, but dream only lying down.
Hippos and otters
Hippos sink to the bottom and rise regularly for air. Otters float on their back on the water, paw in paw, so they stay together.