Some people feel a sudden jolt just as they’re drifting off, as if they’ve missed the bottom stair. It can be startling enough to wake them up again. That jolt is called a hypnic jerk, and it’s one of the most common things that happens as you fall asleep.
The lowdown: Twitching in your sleep is usually a hypnic jerk, a sudden, harmless muscle spasm that occurs as you fall asleep. Around 60 to 70% of people remember having them. Stress, caffeine, tiredness and hard exercise can make them more frequent, and studies show men move more during sleep than women.
A hypnic jerk is a sudden, involuntary twitch that happens as you’re falling asleep. You might also hear it called a hypnagogic jerk or a sleep start. Doctors classify it as physiological myoclonus, which simply means a brief muscle jerk that happens in healthy people. Hiccups fall into the same group. Hypnic jerks can happen at any age and are usually harmless.
Most hypnic jerks happen in the first stage of light sleep, according to The Sleep Charity. Sometimes the whole body jumps, and sometimes it’s just the legs. Many people also notice a feeling of falling, a loud noise or a flash of light at the same moment.
Nobody knows for certain why hypnic jerks happen. Researchers have suggested several theories, but none has been proven, and many jerks seem to come completely at random.
What researchers have found is that some things make hypnic jerks more likely or make them feel stronger:
Verified by Sleep Expert Sammy Margo
"Hypnic jerks—those sudden muscle twitches as you're drifting off to sleep—are completely normal and usually harmless. They can be triggered by stress, anxiety, too much caffeine, or being overtired, all of which keep your nervous system more active than it should be when winding down. We're more like dimmer switches than on/off switches so allow wind-down time."
Twitching can carry on after you’ve fallen asleep. Small movements throughout the night are a normal part of healthy sleep.
When researchers at the Medical University of Innsbruck studied 100 healthy sleepers in a sleep lab, every single one had tiny muscle twitches, known as fragmentary myoclonus. When the same team analysed the group’s video, they found that minor movements were common and rarely accompanied by arousal from sleep.
Twitches happen during REM sleep too. This is the stage most associated with vivid dreaming, and during it, the body’s main muscles are largely switched off. The Innsbruck team found that the movements which do happen in REM are mostly quick, jerk-like twitches.
Studies show that men tend to move more in their sleep than women. In the Innsbruck study, men made a median of 13 movements an hour, compared with 7.9 for women.
Other research backs this up. A later look at the same group found that men also made larger, whole-body movements during the night. A study of people with restless legs syndrome found that men had more periodic leg movements in their sleep, while women tended to report more severe symptoms.
What researchers haven’t worked out yet is why men move more. These studies examined movement throughout the night rather than hypnic jerks specifically, and none of them identified a cause. The known triggers, such as stress, caffeine and tiredness, apply to everyone.
Hypnic jerks can wake you up, especially the stronger ones. Small twitches often pass without being noticed. When jerks become frequent and intense, they can make it harder to fall asleep in the first place.
Movement in the night can disturb anyone sharing the bed, too. In our 2026 UK Sleep Survey, 7% of people said a partner who fidgets a lot is one of their usual reasons for a bad night’s sleep.
If you share a bed, your mattress affects how much movement travels across it. Pocket spring mattresses have individually wrapped springs that move independently, while memory foam mattresses absorb movement. A bigger bed, like a super king bed, gives everyone more room as well.
There’s no proven way to stop hypnic jerks altogether, and the occasional one doesn’t need treating. If they’re happening a lot, it’s worth tackling the known triggers:
1. Get enough sleep
Being overtired is one of the most common triggers, so getting enough sleep is a good place to start. The NHS says most adults need 7 to 9 hours a night.
2. Give yourself time to wind down
Unwinding before bed helps your body slow down. As Sammy Margo puts it, we’re more like dimmer switches than on/off switches. Our guide to creating the perfect bedtime routine and these sleep relaxation techniques have plenty of practical ideas.
3. Think about when you exercise
Regular exercise is good for sleep. A systematic review found that it improves sleep quality. Intense exercise is also a known trigger for hypnic jerks, though the evidence on timing is mixed. One small study found that hard exercise finishing two hours before bed didn’t affect sleep quality, but heart rate stayed higher for the first few hours of the night. If hypnic jerks are a problem, moving tough sessions earlier in the day is an easy thing to try.
4. Stop caffeine at least six hours before bed
Caffeine hangs around in the body for hours. In one sleep study, caffeine taken six hours before bed still cut total sleep by more than an hour. Our guide to caffeine and sleep explains more.
5. Cut back on alcohol
Alcohol is linked to more disturbed sleep. That can leave you tired, and tiredness makes hypnic jerks more likely. Find out more about why alcohol is bad before bed.
6. Find ways to manage stress
Stress and poor sleep tend to go hand in hand. Chronic insomnia is associated with an overactive stress system, and anxiety disorders often come with disturbed sleep. In our 2026 UK Sleep Survey, a racing mind was the top reason people gave for a bad night (37%), followed by stress (28%).
Regular exercise is linked to better resilience to everyday stress. The NHS also offers a short breathing exercise for stress that takes only a few minutes. For more ideas, read our guide on calming anxiety for better sleep.
Most hypnic jerks don’t need any treatment. The Sleep Charity advises seeing a GP if they happen often and come with other problems, such as an injury, bedwetting or confusion when you wake up.
It’s also worth speaking to a GP if any of the following apply to you:
Twitching in your sleep is normal. Around 60 to 70% of people remember having hypnic jerks, and in one sleep lab study, all 100 healthy sleepers had small muscle twitches during the night.
Anxiety and stress can make hypnic jerks happen more often and feel stronger. NHS guidance notes that hypnic jerks can be more pronounced in people with anxiety.
Hypnic jerks are generally harmless and usually settle without any lasting effects. It’s worth speaking to a GP if they happen often and stop you from sleeping, or if they come with injury, bedwetting or confusion when you wake up.
Want to check how well you’re sleeping? Try our Sleep Health Calculator.
