1. X

4. It is now 4 stages, not 5!!!! X

6. Stage 1 typically lasts about 5-10 minutes

7. Also known as Light Sleep

8. Stage 2 typically lasts about 20 minutes
Stage 2 still has theta waves but they show sleep spindles which show stronger brain activity

9. About 45% of sleep is spent in this stage – you pass through this stage several times in a night

10. Stage 3 typically starts 35-45 minutes after falling asleep
Stage 4 “technically” no longer exists
Stage 3 typically starts minutes after falling asleep
Stage 3 and 4 used to be split according to the frequency of delta waves – stage 4 used to be when delta waves were more than 50% of the total

11. Dreaming CAN take place in this stage.
This is the stage where PARASOMNIA disorders occur
Night terrors, sleep walking, sleep talking, etc
Stage 3 and 4 used to be split according to the frequency of delta waves – stage 4 used to be when delta waves were more than 50% of the total

13. Children and Teens tend to be in this slow wave stage more than adults

14. About 20-25% of sleep time is spent in REM sleep
This stage usually dominates the latter half of the sleep cycle

15. Paradoxically, these brain waves are similar to when you are awake

16. The Pons area of the brain is responsible for the paralysis
A 2012 study out of the Univ. of Toronto found that two powerful brain chemical systems work together to paralyze skeletal muscles
The Pons area of the brain is responsible for the paralysis

17. The brain areas involved with long-term memory and emotion are highly active during REM sleep (image from Zeology)

18. If we were not paralyzed, our brain would cause us to act out our dreams.
An experiment done on cats where certain nerves were severed caused the cats to stalk invisible prey, run and jump wildly during REM sleep

19. Websites Used http://www.howsleepworks.com/types_rem.html