Drained and exhausted, you are finally in bed sinking into what will be a deep sleep.

And no matter how many times happens, you never get used to it, it never feels less abrupt,

and it never gets any better. The falling sensation can even be terrifying,

which ends with an involuntary, sudden, and shocking jump.

If this has happened to you at least once, you are not alone. In fact,

up to 70% of people experience this phenomenon, also known as hypnic jerks (or sleep starts).

Nobody really knows what causes these sudden jerks for sure.