You’re perfectly comfy, snuggled up in bed and starting to drift off to sleep when your feet suddenly jerk or twitch, waking you up. Or, even better, maybe you’re already asleep when you sleep partner unknowingly kicks you awake. We’ve all been there, but why do our limbs—feet and legs in particular—flex, jolt and twitch just as we’re falling asleep? And what can be done about it? Well, get cozy because we’re going to lay it all out for you.
What are sleep twitches?
Commonly known as “night twitches” or “sleep starts,” these involuntary muscle movements have a medical name, too: “hypnagogic jerks” or “hypnic jerks” for short. Named for the hypnagogic state between sleep and wakefulness, hypnic jerks are a type of unconscious muscle spasms called myoclonus.¹ (Fun fact: hiccups are another common form of myoclonus). Sometimes these twitches are powerful enough to wake you up and other times they happen while you’re sound asleep. Either way, they can be less than ideal for you or your sleeping partner.
Are hypnic jerks normal?
Good news: they’re very normal and also very common. A 2016 study found that 60-70% of people experience hypnic jerks and that they affect men and women of all ages equally.² Hypnic jerks are also not a symptom of any underlying health conditions. However, if they’re powerful enough to interfere with your quality of sleep on a regular basis, it’s important to speak to a doctor and potentially undergo a sleep study. More pronounced sleep movements may be a symptom of restless leg syndrome (RLS)³ or periodic limb movement disorder (PLMD),⁴ which can usually be improved with medical treatment.
What causes hypnic jerks? Can they be prevented?
Surprisingly, researchers haven’t been able to pinpoint the cause(s) of hypnic jerks. They occur randomly in most people without any clear underlying explanation. Some theories include the “misfiring” of nerves during the transition from alertness to sleep,⁵ and even that they’re an ancient primate reflex intended to stop us from falling out of a tree when we relax! However, the most widely accepted theories are related to lifestyle behaviors that could contribute towards or intensify hypnic jerks.
Exercise stimulates the body and mind, so working out later in the day could make it harder to unwind and fall asleep. Tense muscles and a more active mind could contribute to hypnic jerks, so aim to exercise earlier in the day and save the evening for more relaxing activities.
Caffeine, nicotine and some stimulant medications may make falling asleep or staying asleep very difficult. They may also make nighttime movements more frequent or intense. If you do enjoy coffee, tea, chocolate or anything else containing caffeine, try to restrict it to earlier in the day.
Poor sleep health
An irregular sleep routine and sleep deprivation may also cause hypnic jerks. Try to create a regular and enjoyable sleep routine. Keep your bedroom dark, quiet and free of distractions wherever possible.
Stress and anxiety
A high-stress or high-anxiety lifestyle could be the largest contributing factor. Not only do stress and anxiety stop you from falling asleep, they also cause your mind to stay alert and active, meaning that if you do fall asleep, it’s much more likely that a hypnic jerk will wake you up. This only reinforces the importance of a relaxing nighttime routine.
The bottom line? While sleep twitches are annoying, they’re not dangerous. Try making some positive lifestyle changes and you should notice improvements in overall sleep quality. Happy napping!