why do i twitch when falling asleep

The twitching when falling asleep is known as a hypnic jerk or sleep start. It is an involuntary muscle contraction that occurs as the body transitions from wakefulness to sleep. This sudden twitch often feels like a jolt or a sensation of falling and can involve the whole body or just parts of it. It happens because the brain sometimes sends mixed signals during the process of falling asleep, mistakenly reacting as if the body is falling or losing balance, which causes the muscles to react with a twitch or jerk. Hypnic jerks are normal and very common, although they can sometimes be triggered or made more frequent by factors like stress, caffeine, exercise close to bedtime, sleep deprivation, or certain medications. These twitches are generally harmless and do not indicate any serious condition.