2. Why do we sleep? No one really
knows…but
• Inactivity theory: Moving around at night is
dangerous.
• Saving energy theory: Moving around uses
energy, so we don’t need to eat as much if we
sleep.
• Body repair theory: The body repairs itself when
we sleep.
• Brain plasticity theory: The brain is very
complicated, and may need sleep to help it stay
organized.
3. How long should you sleep every
night?
• We should sleep between 7 and 9 hours every
night.
11. sleepwalking
People usually don’t
remember when they do this.
Sometimes they do dangerous
things like driving a car or
cooking.
Alcohol and stress can cause
sleepwalking.
14. Acid reflux
When you are lying down, acid from your
stomach can come up to your mouth. Not fun.
15. Not enough sleep can make you fat!
• Not getting enough sleep raises your cortisol,
and makes you feel hungry all the time. It also
makes your body store fat.
16. Sleeping pills
• Medicines like hydroxymine can help you
sleep, but we should only use them when we
really need them.
25. Sea otters hold hands when they sleep
so they don’t separate.
26. Questions
• What percent of our life do we spend
sleeping?
• What are some things that can help us sleep?
• What is a bad dream called?
• When do we get “jet lag”?
• What is it called when we can’t sleep?
• How long should we sleep every night?
• What is it called when we sleep for a short
time to get refreshed?