1. Sleep
We spend about one third of our life sleeping!

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.

4. The sleep cycle
REM sleep is
the best for
your body.

5. Circadian rhythms

6. snoring
Snoring is loud and annoying. Do you snore?

7. Sleep apnea
Makes people
wake in the night
because they
can’t breathe. It is
scary, dangerous
and unhealthy.

8. insomnia
People with insomnia
have trouble
sleeping.
Stress and caffeine
can cause insomnia.
Don’t drink caffeine
in the afternoon or
evening.

9. The world record for the longest time
without sleep is 11 days!
In which picture do you think she hasn’t slept?

10. Insomnia is bad for you.

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.

12. Driving while tired is as bad as driving
drunk.

13. Eating before bedtime.

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.

17. Working shifts
Working at irregular
times can mess up
our sleep.
This is bad for us.

18. Taking a nap
Taking a 25 minute
nap can be
refreshing.
But napping too
much can be bad for
you.

19. Nightmares and dreams

20. Babies sleep a lot!
• Babies sleep between 10.5 and 18 hours per
day. They need it for their brain to develop.

21. Exercise helps us sleep

22. Sleep has changed over time
• A long time
ago, people
slept when it
was dark,
and slept 2
or 3 times
every day.

23. Jet lag
• If you travel to faraway countries you will
probably have jet lag because of the change in
time zones.

24. A snail can sleep for three years!

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?