facts about some animal sleep

• Giraffes only sleep 20 minutes per day.

• Some birds can rest one of their two brain hemispheres at a time. Half the brain gets deep sleep and the corresponding eye is closed (the eye on the opposite side of the head), while the other half of the brain is alert to danger with an open eye.

• Bats sleep upside down for several reasons: It makes them less obvious prey, and it allows them to take off at any moment should any threat emerge. Bats must fall into flying because their wings aren’t strong enough for them to alight from a standing position.

• On average, cats sleep 13 to 14 hours during the day, and then mostly roam around at night, which is when they typically hunt in the wild. This is even true of big cats like lions — as kings of the jungle, they don’t need to be constantly alert to protect themselves.