Phase One

• Phase One, also called dozing, begins when you lie in bed. Your heart rate and breathing slow, and your muscles and brain relax. Your brain waves change, and you become unaware of your senses.
  
  

Phase Two

• Phase two occurs immediately after phase one and is a light sleep that lasts about 10 minutes. For this time, the sleeper remains still.
  
  

Phase Three

• During phase three, the sleeper becomes more difficult to arouse. During this phase, he drifts into a deeper sleep and may wake groggy if the sleep cycle is interrupted.
  
  

Phase Four

• Phase Four is the deepest, most relaxed sleep. During this stage, also known as REM sleep, your eyes may move and dreams occur. After the first dream ends, you return to Phase Two and repeat the cycle.
  
  

Fun Fact

• If uninterrupted, the average person will sleep eight hours and 15 minutes. Approximately 75 percent of this time is spent in non-REM sleep.