Why do we twitch and jerk when we fall asleep? It’s a question that makes some people worry, but if this sounds like you, it turns out it’s completely normal.
The sudden jolt many people have when falling asleep or in sleep is called a hypnic jerk.
It’s much more common than you’d think. According to Dr. William Kohler of the Florida Sleep Institute, around 70 percent of people get them. And James K. Walsh, executive director and senior scientist at St. Luke's Sleep Medicine and Research Center, agrees with the assessment that these jolts are very common.
He told NBC News: "A hypnic jerk or sleep starts are a perfectly normal occurrence that is almost universal.
"It involves a total body experience where your muscle contracts therefore your limbs jerk or your body twitches. They generally occur during the transition between wakefulness and sleep."
So why does it happen?
Apparently, there’s different “stages” to every night sleep, which repeat four or five times during each sleep. A hypnic jerk normally occurs as we enter stage 1 of sleep, after being awake.
Apparently hypnic jerks can also indicate that we’re running low on sleep. When our bodies continue with activity when we’re tired, it means certain parts of our nervous system are asleep while others keep working.
So if your partner is sick of what seem like random spasms, just as you’re drifting off to sleep, you can reassure them that it’s nothing to be worried about… even if it’s annoying.