When you are falling asleep, you may feel hypnic jerks, also known as sleep beginnings, which are abrupt, involuntary contractions of your muscles.

These jerks happen during the transition from wakefulness to sleep, which is referred to as hypnagogic (short for hypnic).

Hypnic jerks usually only affect one side of the body, like the left arm or leg, and occur seemingly randomly as you fall asleep.

Why Does My Body Twitch at Random Times at Night?

Although the exact cause of hypnic jerks is unknown, there are some ideas. The same area of the brain that regulates your startle response is where hypnic jerks and other forms of myoclonus begin. It is thought that a misfire between nerves in the reticular brainstem occasionally happens while you fall asleep, causing a reflex that results in a hypnic jerk.

For instance, your brain can erroneously believe that you are actually falling when your muscles fully relax, even though this is a typical aspect of falling asleep, and respond by causing your muscles to twitch. Another possibility is that hypnic jerks are a bodily response to the accompanying dreamlike

Vigorous Exercise at Night

Exercise generally has a positive impact on sleep practically all the time. It’s crucial to understand,

though, that exercise is an energetic activity that increases alertness rather than fatigue. This is why hypnic jerks can result from very intense late-night exercise.