[ELI5] Why does the body twitch when trying to fall asleep if you are really tired?

Question

[ELI5] Why does the body twitch when trying to fall asleep if you are really tired?

In: 3

Answer 1

These movements are called hypnic jerks or sleep starts – they are usually brief and can occur in any part of the body.

They are most commonly experienced, as you say, when a person is feeling tired or drowsy and are often accompanied by a feeling of falling or a sensation of a sudden shock.

There is no one single reason why hypnic jerks occur, but they may be caused by a number of factors, such as stress, fatigue, caffeine consumption, or certain medications. They can also be a normal part of the sleep process and do not typically indicate any underlying health problem.