REM Sleep, or Rapid Eye Movement Sleep, is a phase of sleep found in mammals and birds, in which the eyes dart about behind closed eyelids as dreams become vivid and muscles relax.

While it may sound like it could just be another fun quirk of the human brain, REM Sleep is hypothesized to be beneficial to important functions such as the ability to learn and memorize, and the regulation of mood. A lack of REM Sleep can lead to a loss of appetite, anxiety, mild psychological disturbances or hallucinations, with several reports even indicating an increase of aggression and sexual behavior in laboratory test animals. So, take this as your friendly reminder to treat yourself right and get the necessary required amount of sleep each night.

If you find yourself lacking in REM, perhaps try blasting What's The Frequency, Kenneth? until you can fall asleep. It won't help, I just felt like I had to fit an R.E.M joke in somewhere. Poor effort, I know.