Almost everybody has done, felt or experienced it – the sensation of falling, or a twitch just before you sleep. But why does it happen? And what is going on?
One YouTube channel has had a crack at it, explaining the science behind what really goes on in your head when you’re falling asleep.
We’ll leave the rest of the mesmerising know-how to Discovery World, who dive right in and explain the whole lot.
The technical term for this is a "hypnagogic jerk" - a new one to yell across the bar at someone who cut in front of you, maybe.
The main reason for the sense of falling revolves around the two halves of the brain (one that works when you’re awake and another that looks after you when you’re asleep) handing over signals to one another. The actual muscle contractions might happen because of the amount of dopamine in the body.
There’s also a long-standing evolutionary theory that as apes, the reflex was used to wake up our ancestors if they were falling out of a tree, mid-snooze.
There you go then: another question you always wanted the answer to but never thought to ask. Next week - why we sneeze when exposed to bright light.