Tripping in your dreams and waking up with a twitch happens because your brain thinks you’re dying
A ‘Hypnic Jerk’ also known as a ‘Hypnagogic Jerk’, a ‘Sleep Start’ and a ‘Night Start’ – is an involuntary twitch which happens during hypnagogia. This is the stage just as a person is about to fall asleep and it often causes them to suddenly wake up for a moment.
These ‘Hypnic Jerks’ are a physical resemblance of the ‘jump’ experienced when a person is startled and is often accompanied by a falling sensation. Having irregular sleeping patterns is said to increase the likelihood of this happening.