Why does our eye seem to move rapidly during our sleep

"REM or Rapid eye movement is one of the five stages of sleep, which is charachterised by rapid saccadic movement of the eye. Even though a number of theories have been put forth to explain the rapid movement of the eye during sleep, none have been able to explain the phenomenon conclusively. One of the theories suggest that the movement of the eye may be related to visual images of dream."

 

       A complete cycle of sleep consists of five stages of sleep. REM or Rapid eye movement is one of the five stages of sleep, which is charachterised by the rapid movement of the eye.

       A complete cycle of sleep lasts for around 90 minutes, with the first four stages comprising of non-rapid eye movement(non-REM) sleep. During this period of non-REM, there is little muscle activity and usually the movement of eye is absent, even though the muscles still retain their ability to function normally. REM sleep is the final stage in each cycle of sleep and an average person experiences 4 to 5 REM sleep stages a night. REM stage of sleep is charachterised by saccadic movement of the eye and paralasis of most of the muscles, with increased activity of the brain's neurons. REM sleep during the first cycle of sleep is found to be much shorter than the rest, with REM sleep in seach succeding cycle getting longer.

       The reason for the saccadic movement of the eye during REM is not yet clear even though a number of theories have been put forth. Some theories suggest that such movements of the eye may be related to visual images of dreams. However REM sleep is found in those born blind and in fetuses, thus contradicting the above hypothesis.

       A number of studies have shown that REM sleep is important for consolidation of procedural and spatial memory.

References


[1] http://www.medicalnewstoday.com/articles/247927.php
[2] http://www.webmd.com/sleep-disorders/guide/sleep-101
[3] http://en.wikipedia.org/wiki/Rapid_eye_movement_sleep
[4] http://psych-your-mind.blogspot.in/2011/09/sleep-cycle-whats-really-going-on-while.html