It’s ok, everyone does it… that sudden jolt of your legs or arms when you are basically 85% asleep.

You can always kind of remember it happening, but also you’re kind of not sure?

Well have you ever wondered why this happens?

Scientists have finally figured it out. They’ve called it the ‘hypnic jerk’, and there’s a few different causes for it.

It feels different from person to person, but generally people describe it similar to the feeling of falling.

External causes such as caffeine and tobacco can cause these jerks, so it’s been recommended to avoid these type of things before bedtime.

Sleep deprivation and drug use can also cause similar feelings.


The hypnic jerk is most commonly seen when someone falls asleep quite quickly, or during the day, or after they’ve been completely exhausted.

So now you know.