You know when you have fallen almost asleep, but then you just jerk back awake?

This has a name. It's called a hypnic jerk, and it's an involuntary movement.

It's kind of like getting the hiccups. It doesn't always wake you up, but even if it doesn't it might wake up whoever you are sleeping near. Now, researchers aren't totally sure what causes these jerks.

Some think that it could be when your body relaxes, your brain mistakenly believes that you are falling, so it startles you awake. Like, "Don't fa- just catch on to something."

Maybe it could just be your nerves misfiring as well, but whatever the cause, studies have shown that they happen more often when you consume a lot of caffeine, are under stress, or exercise really hard. All of those are things that make you more alert and hypnic jerks happen on that brink between alert and asleep.

Now, more generally, research shows that not drinking caffeine at least six hours before bed, or trying stress management techniques like mindfulness, could help improve your sleep. And maybe it would help keep those hypnic jerks to a minimum if it bugs you or if it wakes up your partner, or your dog.