NUMBER OF HOURS OF SLEEP

• First of all, there is a big difference between herd animals and predators. 
  Herd animals such as zebras, bison and wild horses usually sleep briefly, in powernaps spread over day and night. After all, they must be able to flee quickly in case of danger.

  Predators, such as tigers and lions, sleep just a lot and for a long time (up to 20 hours a day!), especially during the day. They must of course be wide awake at night to hunt.  

• Any idea which mammals sleep least of all? They are elephants and giraffes. They manage to get by with about four hours a day. A great contrast to bears. They take extremely long naps, up to 8 months at a time! 
• Pets such as domesticated cats and dogs largely adapt to the rhythm of humans. Yet cats sleep much more than us. They spend no less than 70% of their lives asleep.  

• Another special case: the dolphin. It never really sleeps completely. Dolphins let only one half of their brain sleep at a time, so they always keep literally one eye open. They do so for 8 hours a day.

DIFFERENCE IN SLEEPING POSITION

• What about the sleeping posture of animals? You probably already knew that bats hang upside down to sleep. Panthers like to sleep high up in a tree on a branch and cows can sleep standing up. But... a cow will only dream when she's lying down.

  Hippos, in turn, put themselves in the water for a nap. They sink to the bottom of the river or lake and occasionally come up to take a breath. But the cutest sleepers are otters. They float quietly on their backs in the water, 'paw in paw'. They do that so they don't drift away from each other. Romantic, isn't it?