NREM Sleep
Understanding the Four Stages of Non-REM Sleep
The period of NREM sleep, or non-REM sleep, consists of four discretely independent stages, each one lasting anywhere from 5 to 15 minutes. A complete NREM sleep cycle typically lasts for about 90 to 120 minutes and sleep quality changes as the body transitions from one NREM sleep stage to another.
Sleep Stage I
Studies show that there is a 50% reduction in brain activity between wakefulness and NREM sleep stage I. A person in stage I may feel drowsy with eyes that are closed, but may feel as if he or she has not slept if aroused or awaken from this very light stage of NREM sleep.
Sleep Stage II
Sleep stage II a light stage of non-REM sleep that consists of intermittent and spontaneous periods of muscle tone mixed with periods of muscle relaxation. In this stage, the heart rate slows as body temperature decreases in order to prepare for deep sleep.
Sleep Stages III and IV
Also called delta sleep, or deep sleep, sleep stages III and IV of the NREM sleep cycle is where all eye and muscle movement ceases. It is difficult to wake an individual in the third or fourth stage of NREM sleep, where anyone awoken from these stages may feel groggy and disoriented for several minutes.
If you are concerned that you or someone you love may have a sleeping disorder consult with your doctor for professional diagnosis and treatment.
Disclaimer: Statements contained herein have not been evaluated by the Food and Drug Administration. These statements and products are not intended to diagnose, treat and cure or prevent disease.
