It tends to happen when you’re just about to drift off where your legs or your body will suddenly twitch or jump.
It might momentarily disturb your sleep but it usually doesn’t affect your ability to instantly return to the land of nod. But what are these fleeting moments called and why do they happen?
Hypnic jerks (also referred to as sleep starts) are involuntary muscle contractions that occur infrequently for most of us. We don’t always forget about them either. It’s estimated around two thirds of people remember twitching in their sleep the following morning.
There are some lifestyle tweaks you can make to reduce your chances of experiencing hypnic jerks. For example, adjusting your evening routine and cutting out caffeine, late exercise and other stimulants can help.
Sleep expert Lisa Artis, deputy chief executive of The Sleep Charity, tells us more.
What are hypnic jerks?
“If you’ve ever woken yourself up with a jump, this is called a hypnic jerk,” Lisa explains.
“These are sudden, involuntary muscle contractions that occur as you begin to fall asleep. These twitches can affect the entire body or just the legs and they’re often accompanied by a sensation of falling, a loud noise or a flash of light.”
Hypnic is short for hypnagogic, a term that describes the transition between wakefulness to sleep, and that’s typically when you might experience a hypnic jerk. But you can also experience them during light sleep.
Lisa adds that hypnic jerks are part of the parasomnia group and are quite common. “It’s estimated that 60-70% of people remember having them,” she explains.
“If they happen infrequently, they’re generally not distressing and don’t affect your sleep long-term.”
What causes hypnic jerks?
While the exact cause of hypnic jerks isn’t fully understood, there are contributing factors that can make them more likely.
1. Caffeine in the afternoon or evening
Having a caffeinated drink late in the afternoon or close to bedtime can increase your chances of experiencing hypnic jerks as they can heighten your brain activity, says Lisa.
Caffeine acts as a stimulant and it can disrupt your transition from wakefulness to sleep.
It’s thought that caffeine can also confuse your brain into misinterpreting muscle relaxation as a falling sensation. This can then cause your muscles to involuntarily jerk or twitch.
2. Exercise in the evening
There are tons of reasons why exercise is great for your mind and body but working out late in the evening is not good news where your sleep is concerned.
Being highly active in the evening can leave you feeling more alert than tired. It can also be a trigger for hypnic jerks as it leaves you in an energised state, making it more difficult for your body to unwind.
If you still want to fit your workout in, find out how to exercise for better sleep.
3. Stress and anxiety
When you are feeling stressed or anxious, this has the effect on your body of keeping your cortisol levels elevated during the night, making it harder to relax.
It’s also thought stress and anxiety can disrupt the transition from wakefulness to sleep. Lisa tells us more.
“Stress and anxiety are common reasons for sleep disturbances,” she says. “They can affect your sleep patterns and this can lead to hypnic jerks when you eventually fall asleep.”
4. Sleep deprivation
When we’re not getting enough sleep, whether temporarily or as part of an ongoing condition such as insomnia, we’re more at risk of hypnic jerks.
Sleep deprivation can disrupt the normal transition into sleep so there’s an increased chance that you might experience twitching as you drift off.
Being overtired is also a common reason why people can experience hypnic jerks. Interestingly, sleeping in an uncomfortable position is another culprit.
It’s thought fatigue can cause the body’s nervous system to misfire, and this can lead to sleep twitches.
5. Restless legs syndrome
For most people, twitching in your sleep isn’t usually a sign of an underlying condition. Instead, they’re simply an occasional and unpredictable part of drifting off to sleep.
But, if experiencing your muscles twitching and jerking at night is a regular occurrence for you, this could be a symptom of a sleep disorder such as restless legs syndrome.
“It is usually not necessary to seek treatment for hypnic jerks unless they occur frequently and are accompanied by other complaints such as physical injury, bedwetting or confusion when awakening (these symptoms can be experienced with restless legs syndrome, for example),” Lisa says.
“In these instances, you must visit your GP.”
How to stop twitching at night
While you can’t completely avoid experiencing the occasional hypnic jerk, you can take steps to minimise their regularity.
Stick to a regular sleep schedule
When you regularly vary what time you go to bed and get up on a morning such as having a lie-in whenever you can, this can make experiencing twitching while you sleep more likely.
“Getting regular, quality sleep is the best way to reduce hypnic jerks so it’s important to tackle the root causes of sleep disturbances and sleep deprivation,” Lisa explains.
“Establish good bedtime habits including going to bed and waking up at the same time every day, even on weekends, to programme your body clock.”
Take steps to de-stress before bed
“Manage stress and anxiety by using relaxation techniques such as mindfulness meditation, deep breathing exercises or yoga to help calm the mind and body,” Lisa suggests. “This will make sleep transitions smoother.”
Creating a bedtime routine that incorporates winding down by reading or listening to relaxing music can be great for signalling to your mind and body that it’s almost bedtime.
Getting outdoors for fresh air or being active during the day can also help to regulate your sleep-wake cycle.
Avoid stimulants
“Avoid caffeine or other stimulants such as nicotine in the hours leading up to bedtime to prevent sleep disruption and minimise twitching at night,” Lisa advises.
“These stimulants can heighten brain activity, increasing the chances of hypnic jerks.”
Having caffeine in the evening can interfere with your ability to sleep soundly so try to have your last cuppa at least six hours before bedtime.
Similarly, nicotine can impair your brain’s ability to wind down, so having a daily cut off point for nicotine could help you to sleep better and twitch less.
