1. Obj: Describe the stages of sleep and list several sleep problems.
Ch. 5 S. 2 Sleep and Dreams
Obj: Describe the stages of sleep and list several sleep problems.

2. The Stages of Sleep
Using an electroencephalograph (EEG – measures brain-wave patterns) researchers discovered that we sleep in stages.
When we are awake, we emit beta waves, which are short and quick.

3. As we relax, we move from beta to alpha waves.
Stage 1 – light sleep that produces the theta waves typical of relaxation with dream-like images that resemble photographs. Lasts 30 or 40 minutes.

4. We move to stage 2, 3 and 4, which are deeper
We move to stage 2, 3 and 4, which are deeper. And during stages 3 and 4 the brain produces delta waves – the slowest of the four patterns.
Stage 4 is the deepest, meaning it’s the one that is hardest to wake up from.

5. After 30 minutes of stage 4, we quickly journey backward to stage 1.
At this point we begin the last stage of rapid-eye-movement sleep (REM)
During a typical 8 hour night, most people go through these stages about 5 times, which is one sleep cycle.

6. Why Do We Sleep?
To revive the tired body and to build up resistance to infection. We also think it helps recover from stress.
If deprived of sleep, you become irritable, can’t focus eyes, and have speech problems.

7. When deprived of REM sleep, people learn more slowly than usual, and forget more rapidly.
REM sleep may also help with brain development in infants and act as brain exercises for adults.

8. Dreams It is during REM sleep that we have our most vivid dreams.
We can dream during the other stages, but the images don’t make as much sense.
Freud believed that people dreamed in symbols of what they really wanted.

9. Sleep Problems
Insomnia – the inability to sleep. Usually caused by stress.
Nightmares – caused by a variety of events such as work or even depression. Occur in REM sleep.
Night Terrors – more severe than nightmares but are seldom remembered. Usually occur in Stage 3 or 4.

10. Sleepwalking – roaming about almost nightly during stages of deep sleep.
Sleep Apnea – breathing interruption that occurs during sleep. They start breathing again when they sit up and gasp for air. They’re usually not fully awake, so may not remember it.

11. Narcolepsy – a rare sleep disorder in which people fall asleep no matter what time it is or where they are. Believed to be a genetic disorder.