Sleep and dreams


 * Cows can sleep standing up but they can only dream while lying down.
 * Ants don't sleep.
 * Reading the word "yawn" or "yawning" makes many people feel the need to yawn.
 * It takes about seven minutes to fall asleep. If you fall asleep in any less time you are said to be sleep deprived.
 * A person can only go about ten days without sleep, then they may die.
 * You are tallest right after you wake up but you shrink during the day from the force of gravity.