This application is not fully accessible to users whose browsers do not support or have Cascading Style Sheets (CSS) disabled. For a more optimal experience viewing this application, please enable CSS in your browser and refresh the page.
Imagine that you're relaxed and drifting off to sleep when suddenly an arm or leg twitches and you have the sensation of falling out of bed. If this has happened to you, you've experienced what sleep specialists call a hypnic jerk or sleep start. Sleep starts happen in normal, healthy people and don't ordinarily require any medical treatment. However, certain medical conditions can make you jump in your sleep and should be evaluated by your physician.
It is during REM that our body is paralyzed, so that we are unable to act dreams out. This muscle relaxation, called atonia, may sometimes occur while you are awake. As such, you will be unable to move, even if you are conscious. This is one of the common features of sleep paralysis.