Psychology Unit VI: Stages of Sleep

STAGES OF SLEEP

Stage One

• kind of awake and asleep
• a few minutes
• eyes roll slightly
• brain produces Theta waves

Stage Two

• "baseline" of sleep
• part of a 90 minute cycle and occupies about 45 - 60% of sleep
• more Theta waves get progressively slower
• begin to show sleep spindles

Stages Three to Four 

• slow wave sleep
• produce Delta waves
• if awoken, can be groggy
• may last 15 - 30 minutes 
• "Delta" sleep is deepest stage of sleep
• restore body's growth hormones and good health

Stage Five REM Sleep

• Rapid Eye Movement
• called Paradoxical Sleep
• brain is active
• dreams occur
• body is essentially paralyzed 
• composes about 20 - 25% of a normal night's sleep
• quicken breathing, heart rate, and brain waves
• vivid dreams can occur
• from REM sleep, you go back to Stage Two