Why do you twitch?

I was asked by a patient why they twitch at night as they are falling asleep.  I assured them that they are not alone as this often happens to many of us during the initiation of sleep.  The falling sensation or twitch is known as a hypnagogic myoclonic twitch. It is a benign occurrence.  In preparation for sleep, your muscles begin to relax and your brain senses these relaxation signals and misinterprets them, thinking you are falling. As a result, the brain then sends signals to the muscles in your arms and legs in an attempt to jerk you back upright or prevent you from "falling".  Some people describe having a dream about "falling" of flying in accompaniment of the twitching sensations.  Of course dreaming only occurs during the REM stage of sleep, so what they are describing is more like a daydream or a hallucination that is tied into the bodies sensation.

Recently there has been some speculation in the sleep community that these jerks can be tied to sleep anxiety, fatigue, and discomfort. People having trouble sleeping or "can’t get comfortable" in bed appear to experience the sensation more often than others. It is especially more common with people who are trying to fight falling asleep or are sleep deprived for more than 24 hours.  The thought is that lack of sleep causes more confusion between muscles and the brain. The muscles keep trying to relax and shut down, while your brain fights to stay awake because of the continued misinterpretations of falling or loosing balance.

Our bodies go through several stages in preparation of sleep, and the twitches are just part of the process.