Sleep

- a state of conciousness
- less aware of our surroundings
- Conscious
- Subconscious
- Unconscious

Biological Rhythms
- Annual Cycles: seasonal variations (bears hibernation, season affective disorder)
- 28 days: menstrual cycle
- 24 hour cycle: our circadian rhythm
- 90 minute cycle: sleep cycles

Circadian Rhythm
- 24 biological clock
- body temp and awareness changes throughout the day

Sleep Stages
- 5 identified stages
- 90 to 100 mins to pass through the stages
- Brains waves will change according to the sleep stage you are in
- First four are known as NREM sleep
- The fifth stage is called REM sleep



Stage 1
- Kind of awake and kind of asleep
- Only lasts a few minutes, and you usually only experience it once a night
- Eyes begin to roll slightly
- Your brain produces Theta Waves (high amp, low frequency) (slow)

Stage 2
- This follows Stage 1 sleep and is the "baseline" of sleep
- This stage is part of the 90 minute cycle and occupies approximately 45-60% of sleep
- More Theta Waves that get progressively slower
- Begin to show sleep spindles.. short bursts of rapid brain waves

Stage 3 and 4
- Slow wave sleep
- You produce Delta waves
- If awoken you will be very groggy
- Vital for restoring body's growth hormones and good overall health

Stage 5: REM Sleep
- Rapid Eye Movement
- Often called paradoxical sleep
- Brain is very active
- Dreams usually occur in REM
- Body is essentially paralyzed
- Composes 20-25% of a normal nights sleep
- Breathing, heart rate and brain wave activity quicken
- Vivid dreams can occur
- From REM, you go back to Stage 2