1. Sleeping …
Do we need sleeping ?

2. Why do we need sleeping?
How many hours do we need?
What could happen if we don’t sleep?

3. Let’s answer one of the questions:
We need sleep for our body to relieve
stress, to grow, and also to balance our
bodily chemicals.

4. What could happen if we don’t sleep?
A real case!
 Randy Gardner, a 17-year-old high-school student from San
Diego, stayed awake for eleven complete days. Although he felt
nauseous at times, had difficulty reading, and suffered temporary
memory lapses, he had no long term emotional or physical side-
affects of the experiment. Measurements have been taken,
however, to prove that there are some chemical changes during
sleep deprivation that concludes the fact that our body needs
sleep

5. Why does it happen?
 Melatonin is a hormone secreted from the pineal gland in the
center of our brain. It is released when our eyes begin to register
that the sun is beginning to set and darkness begins to fall. This
is what makes you go to sleep and is also used in our body to
regulate our sleep-wake cycles. If you wonder why older people
tend to sleep less then younger people, it is because the amount
of melatonin produced in our body seems to lessen as we age.

6. The two types of sleep
REM (Rapid Eye Movement ) – NREM
(Non-Rapid Eye Movement)
 In total , there are four stages of sleep :
3 for NREM
1 for REM

7. What is NREM ?
 NREM is the first type of sleep you enter into when you
first fall asleep. Most of our time asleep is spent here.
 It is split into 3 stages, with each stage taking you deeper
and deeper into sleep.

8. NREM Stage 1
This is the first stage of NREM, starting
from the moment you first fall asleep.
Your brain begins preparing you for the
deep sleep ahead. Your muscles relax and
your breathing becomes slow and steady.
It’s a very light sleep. If you wake up at
this stage, you might not even know that
you had just been sleeping.

9. NREM Stage 2
 Stage 2 is the next stage of sleep following on
from stage 1. Here you’re in a deeper sleep than
in stage 1. You can still be woken up pretty easily
at this stage but you will certainly know that you
had just been sleeping.
 Here your body functions slow down even more
and prepares for the next stage of sleep.

10. NREM Stage 3
 It is the last stage of sleep. Here your body is in
a deep sleep. Waking someone from this stage
would be pretty difficult and if you managed it,
they would feel very groggy, tired and
disoriented. They certainly wouldn’t thank you for
it!
 Dreams are more common in this stage than
other stages of NREM sleep, although you would
probably only remember fragments of your
dreams if anything at all.

11. What is REM ?
 REM sleep is the second type of sleep, often kicking in only
after a full cycle of NREM sleep.
 This is the stage where most dreaming occurs. REM is
sometimes called paradoxical sleep because brain scans of
people who are in REM show that their brains are very
active, despite the fact they’re fast asleep.
 However, while your brain is active, only your eyes can
move. There are exceptions though. Some people have a
condition called REM Disorder where by their body is not
paralysed during sleep and they can actually act out their
dreams.
 From the age of 2 onwards, we spend around 20% – 25%
of our sleep in REM where as newborns spent around half
of their time asleep in REM.

12. Why do we have two types of sleep?
It is still a mistery why there are two kinds of sleep as we
should all have a NREM sleep .
The purpose of REM sleep is not fully understood. Some
scientists think REM sleep may have something to do with
the role of acting on our memories and making sense of
the day, which could explain why newborns have more
REM sleep than others as they explore their new world.

13. Now that we have learned a lot more
about sleeping , let’s see what you can
remember …
Copy these questions in your folder and
answer them!!!
Who will remember more ???

14.  1) Why do we need sleeping?
 2) What is Melatonin used for in our bodies?
 3)How many types of sleep are there? How do
you call them?
 4) Describe “with your own words” each of their
stages .
 5) Do scientists know why there are two kinds of
sleep ? Which is healthier?
Good luck!!