Sleep Centers of Middle Tennessee

What are the Types of Sleep?

Posted on 14 Apr 2011 - 4:10 PM

There are two distinct types of sleep: 1) Rapid Eye Movement (REM) sleep (also known as dreaming sleep), and 2) Non-REM (NREM) sleep. Sleep is composed of 5 stages. Stages I-IV are known as NREM sleep (with stages III & IV being deep sleep). Stage V is REM sleep. Humans generally alternate between REM and NREM in 90-110 minute cycles. The process is as follows: once asleep, we move into stage I, then cycle through stages II – IV in roughly 30-40 minutes; we cycle back briefly through stage III and II, then REM. This process normally occurs 4-5 times per night.