1. By: Taylor Johnson, Megan Kirkpatrick, Nicole Colonna, and Alex Angeli

2. Sleep Cycle

3. An Introduction to Sleep The sleep/wake cycle is also known as a person’s circadian rhythm and consists of several 90 min cycles throughout the night.

4. Stage 1 Considered a transition period between awake and asleep. This stage lasts around 5-10 minutes. Light sleep Theta waves are produced Muscle Activity Slows Down The ability to still be aware of surroundings Occasional muscle twitching (Hypnic Jerk)

5. Stage 2 Lasts for approximately 20 minutes as the brain begins to produce sleep spindles. Breathing pattern slows Heart rate slows Decrease in body temperature

6. Stage 3 This is a transitional period between light sleep and deep sleep and lasts around 10 minutes. Deep sleep begins Slow Delta Waves begin

7. Stage 4 Referred to as delta sleep, this deep sleep lasts around 30 minutes. Bedwetting and sleepwalking Strong delta waves Rhythmic breathing Limited muscle activity

8. REM Rapid Eye Movement refers to the most productive stage of sleep. It lasts about 5-10 minutes. Most dreaming occurs Heart rate increases Brain activity increases Voluntary muscles become paralyzed

9. Normal Cycle Progression 1 2 3 4 3 2 REM 2 3 4 3 2 REM 2 3 4 REM

10. Sleep Abnormalities Insomnia Sleep Apnea Narcolepsy Sleepwalking Night Terrors

11. Source Blair-Broeker, Charlie, and Randy Ernst. Thinking about Psychology. Second ed. New York: Worth, 2003. Print