1. It is still a bit of a mystery why our bodies need sleep. If you lived 100 years ago, studies estimate you would be getting 20% more sleep than you do now. A typical night’s sleep is in 90 minute cycles. About 25% of each cycle is Rapid Eye Movement. It is believed that this is when the brain takes care of memories and other “housekeeping” tasks.

2.  Your large muscles can’t move  Your pulse, breathing and temperature go up  Your eyes dart back and forth  Long brainwaves  Body temperature drops, breathing and pulse slow  Dreams are less intense  Sleepwalking and Sleeptalking can occur

3.  Increased irritability  Decreased motivation, memory and concentration  Decreased creativity and spontaneity  Increased proneness  Greater likelihood of problems such as upset stomach or headaches

4. Certain substances disrupt sleep Caffeine keeps you awake, and lasts for hours Alcohol may make you sleepy at first, but is suppresses REM sleep and may make you wakeful later in the night Nicotine prevents sleep even better than caffeine Diet pills often contain sleep disruptors

5. Horses, cows and snakes don’t close their eyes when they sleep. Since the invention of the electric light bulb in 1913, Americans average 1 ½ hours less sleep per day

6. Sleeping in an upright position is unnatural for humans and results in poor quality sleep A 7% increase in traffic crashes occurs in the week after the shift to daylight savings time, when we lose an hour of sleep. Humans will die from lack of sleep sooner than from lack of food

7. The immune system is most active during sleep, making extra sleep important when sick All mammals sleep. Grazing animals sleep 3 hours a day while bats sleep 20. Some birds can sleep while flying, taking naps while they glide.