1. And, no, you don’t get to sleep in class…so don’t ask!

2. The infamous biological clock is real

3. Sleep Humans work on a 24-hour circadian rhythm Circa means “about”
Dian means “a day”
So, circadian means “about a day”
In that day we have a high point and low point

4. Sleep The lowest point for most people is between 3 and 5 am
This means that between 3 – 5 am our body has:
the lowest blood pressure
lowest heart rate
And, we are at our weakest

5. And, what are we usually doing at that time?
Sleeping!

6. Sleep Our sleep is divided unevenly between two types:
REM
Non-REM (NREM)
REM stands for rapid eye movement
We are in NREM for about 75% of our sleep and REM for about 25%.

7. Sleep
We study what happens during our sleep using EEG (electroencephalograph) which is a device that registers the brain activity
EEG shows brain waves while we are awake
But for our interest it also shows brain waves while we are asleep.

8. Sleep NREM is broken into four stages
As you sleep your brain waves get larger and have lower frequency
Once you go through the four stages it reverses and goes up and down through the night
One cycle (down, up and back down) takes about an hour and a half

9. Sleep
Stage One  slightly awake, slightly asleep. EEG shows low frequency
Stage Two  a bit lower frequency. This is when that weird unintentional movement occurs.
Stage Three  lower frequency than two. Hitting a deeper sleep
Stage Four  Deep sleep, this is the lowest frequency. This is when sleep walking and talking occurs

11. Sleep Once a person hits stage four the cycle goes back up.
Cycle goes like this: 1, 2, 3, 4, 3, 2, REM, 2, 3, 4, 3, 2, REM, etc.

13. During what stage do we dream?
REM

14. Sleep REM is paradoxical
It looks like one thing is true but another is actually true
When looking at an EEG of REM it looks like an EEG of someone who is completely awake, but our body is completely immobile

15. Sleep
When a person feels that they are being attacked or being chased and can’t get away or can’t move, it is because they really can’t move.
When watching someone sleep during REM cycles you can see the movement of their eyes but what you’re actually seeing is the movement of their eyes to what they are seeing in their dream.
The first REM is about 5-10 minutes but gets longer each time it gets to that part of the cycle.
If allowed to wake up naturally the last stage would be stage one

16. Comparison REM Rapid Eye Movement Increases in length during the night
Vivid dreams
Nightmares
Paralyzed body
NREM
Non Rapid Eye Movement
Decreases in length during the night
Vague, partial images and stories
Incubus attacks
Sleepwalking/talking occur

17. Sleep Incubus attacks are also known as night terrors
Because our body works on cycles we are normally prepared for dreams every 90 minutes
Since terrors occur during NREM we aren’t prepared for them
Body completely flips out – breathing and heart rate become erratic

18. Incubus also means “to have a devil on your back”
Sleep
Incubus also means “to have a devil on your back”

19. Why do we sleep?
Restoration Theory – sleep is a necessity for the body; cools body off
Adaptive/Non-respondent Theory – sleep has become natural because we didn’t want bad things to happen to us (prehistoric times)

20. Why do we sleep?
REM Theory – we need the REM sleep in order to function
Dream Theory – we need to dream to help solve problems or take emotions unable to react to or carry out in real life, and reacts