For some it can be a worry to find out that they twitch during their sleep, but if this sounds like you then don't fear - it's perfectly normal, according to sleep experts.
That sudden jolt you might experience is extremely common - so much so that is has a name, hypnic jerk.
According to one medical director, Dr. William Kohler of the Florida Sleep Institute, as many as 70 percent of people experience them.
Kohler's reassurance has been backed up by James K. Walsh, executive director and senior scientist at St. Luke's Sleep Medicine and Research Center who reiterated just how normal such incidences were.
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, some science. When the body goes to sleep it passes through different stages. There's Stage 1 as it begins to fall asleep, then comes Stage 2 and 3, before moving into rapid eye movement (REM) sleep.
This cycle will repeat four or five times during your slumber.
Also known as a hypnagogic jerk, a hypnic jerk will occur between being awake and Stage 1.
They last between last half a second or less and aren't considered dangerous at all, and so not too much research has been done about them.
Rafael Pelayo, a sleep specialist at the Stanford Sleep Medicine Center, spoke to Mic about hypnic jerks and, according to him, you'll recognise them as movements such as swinging your arms or kicking your legs involuntarily.
If you're sitting upright and start dozing, meanwhile, you might snap your head back.
Hypnic jerks are also telltale signs that you're sleep deprived, but you are making your body continue to work and stay awake when it doesn't want to be.
When this is happening it means that the body transitions from Stage 1 straight into REM when you go to sleep, which is also when you may start to have more vivid dreams.
Pelayo also explained that when our bodies are having to continue with activity when they're sleep deprived, it'll mean that certain parts of the nervous system will be asleep while others remain awake.
It makes the nervous system's control of our muscle movements during sleep different than than when we're awake, which is why our limbs twitch.
So there you have it, try not to worry if you find yourself twitching in your sleep - although speaking from experience, those of you with partners may want to worry if you accidentally kick them.
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