You may wake up with a sudden jerk in your arm or leg just after falling asleep. This sudden movement is called sleep twitch or hypnic jerk. Some people experience hypnic jerks while awake. Read on to know why people twitch in their sleep, causes of hypnic jerks, how to stop them, and when you need to consult a doctor.
What Is a Hypnic Jerk?
Did you ever wake up with a sudden jerk or jolt of a body part while drifting off to sleep? This is called hypnic jerk or sleep start or hypnagogic jerk.
A hypnagogic jerk is a strong, sudden involuntary twitch or muscle contraction that occurs as you are beginning to fall asleep and you wake up startled or scared. The term hypnagogic represents the transition between wakefulness to sleep – a phase when these involuntary contractions occur. If you experience the same phenomenon upon walking up, it is called a hypnic jerk.
Hypnic jerks are sometimes called myoclonic jerks or sleep twitches. A myoclonus is a category of rapid, involuntary muscle movements. Another type of myoclonus is Hiccups. Whether it is a hypnic or a hypnagogic jerk, both affect only a part of the body like a leg or an arm. Most common sleep starts involve a sudden jolt in the entire body. While vocalization or a sharp cry may occur in some cases.
Awakening due to these sudden movements is often associated with a short mental image or say a dream image that you’re kicking a football or you’re falling from your bed. A hypnic jerk doesn’t cause serious complications or side effects and is not considered a serious disorder.
Symptoms of a hypnic jerk are:
- Sensory flash
- Falling sensation
- Jerk or jolt of a body part or muscle
- Rapid heartbeat and quickened breathing
- Hallucination or dream that leads to fall or jump
What Do Hypnic Jerks Feel Like?
A hypnic jerk is a single jolt that occurs at random just as you’re falling asleep. It can be mild and nothing to worry about as it typically affects only one side of your body such as the left leg and arm. Most hypnic jerks are painless. A lot of people sleep through hypnic jerks and are aware of it only when informed by their sleep partner.
You may also experience multiple hypnic jerks in succession that bring your body to alertness and delay the onset of sleep. Although known to occur at any age, a hypnic jerk is more common among adults, especially those who take more caffeine or are highly stressed.
Some people experience hypnic jerks along with sensations like –
- Pain or tingling (rare)
- Feeling of falling
- Dream or hallucination or see flashlights
- Snapping or banging or snapping sound
What Causes Hypnic Jerks?
The exact cause of hypnic jerks is not yet known to researchers. Existing literature on this subject explains that a hypnic jerk or a sleep start occurs in the same brain region responsible for you to feel scared or startled.
According to researchers, when we are drifting into sleep, sometimes a misfire occurs between nerves in the reticular brainstem that triggers a reaction, which leads to a hypnic jerk.
How does this misfire occur?
Well, say you are trying to fall asleep and your muscles relax completely. But, your brain may assume you are falling down from a certain height and react to it by involuntary muscle contraction. Hypnic jerks may not always be spontaneous, it can also be a physical reaction to a mental image or hallucination or dream-like imagery that is associated with them.
A visual sleep start occurs when you see or have a sensation of blinding light coming from your head or inside the eyes. Some people hear a loud snapping noise coming from inside the head, which refers to an auditory sleep start. ‘Sensory sleep starts’ occurs when you experience only sensory phenomena without any jerk in the body.
Researchers have identified some factors that increase the risk of experiencing a hypnic jerk and are listed below:
Lack of restful night sleep due to insomnia or hectic work schedule or poor sleep quality leads to sleep deprivation. Leaving your sleep unaddressed may lead to hypnic jerks besides poor concentration and low mood.
Trouble sleeping and lack of regular sleep overall, whether due to chronic insomnia or a poor night’s sleep, can both lead to sleep deprivation. Among other unwanted side effects, like poor mood and focus, sleep deprivation may increase your risk of jerking in sleep.
Stress and Anxiety
Main hypnic jerk causes are stress and anxiety. But what does it mean if you experience hypnic jerks or body jerks due to anxiety?
People diagnosed with anxiety disorder and stress are highly likely to experience insomnia, which leads to sleep deprivation and consequently hypnic jerks. Excessive stress and anxious thoughts increase the levels of stress hormone – cortisol that deprives you of good quality sleep. When you don’t relax while sleeping, it disturbs the transition between wakefulness and sleep, which is why you twitch before falling asleep.
Again people who frequently experience hypnic jerks develop anxiety around sleeping at night, which in turn increases sleep deprivation and frequency of hypnic jerks.
No doubt, exercise improves physical and mental health and sleep quality. However, it makes you feel more alert and not exhausted. So, vigorous exercise especially in the late evenings may increase the frequency of sleep starts.
Excessive Caffeine or Nicotine Consumption
Taking caffeine or nicotine products before bedtime can increase your risk of twitching before falling asleep. Both nicotine and caffeine stay in our system for long hours and keep our brain alert and delay the onset of sleep. Those who drink coffee a full six hours before bed also have trouble falling asleep.
So avoid such stimulants in the late afternoons and evenings to prevent sleep-onset insomnia.
One study suggests that the origin of hypnic jerks dates back to our evolutionary ancestors. As per the hypothesis, sleep twitching helped primates readjust their sleeping positions or positions before they entered a deep sleep state. When sleeping in uncomfortable places like tree trunks or rocks, the brain interpreted the transition to relaxation as a threat to their survival. A hypnic jerk prevented the primates from falling out of a tree or getting hurt during their restful night’s sleep.
Hypnic Jerks in Children
Children and babies too experience hypnic jerks, but it is more common in adults according to the American Academy of Sleep Medicine. The frequency and intensity of sleep start is less in children because most factors associated with hypnic jerks like alcohol or caffeine intake or vigorous workouts are not relevant to them.
Are Hypnic Jerks Dangerous?
No. Hypnic jerks are sudden and quick and are not linked to any side effects or serious complications. They only occur during the transition from wakefulness into sleep and may occur while you are asleep or awake. These sleep starts are not considered a disorder.
According to research, up to 70 percent of people experience hypnagogic jerks, but not every one of these contractions will forcefully wake you up. A lot of people sleep through many of the sleep twitches.
If the frequency of hypnic jerks is too high it can cause irritation and anxiety around sleep itself. You may not want to sleep at all. If you are sleeping with your partner, children or sibling, or pet, you may accidentally injure (not very serious) them and yourself too.
You should refer to a doctor if you are experiencing sleep deprivation or insomnia, or any other sleep difficulties due to hypnic jerks.
Consult your doctor immediately, if you frequently experience persistent muscle contraction in different parts of your body during the day or night. It could be a nervous system disorder, epilepsy, or another concerning issue.
How to Stop Hypnic Jerks?
Hypnic jerks while awake or asleep need no treatment. All you need to focus is on preventing them from happening.
Reduce Your Stress and Anxiety
Lower the stress and anxiety, lower the frequency of hypnic jerks. Try to relax your mind and body by practicing relaxation techniques like –
These three calming activities are popular for decades in relieving stress and are supported by a bulk of studies. Deep breathing includes – inhaling for 10 counts, holding for 5 counts, and exhaling slowly for 10 counts. Repeat this a couple of times to slow your heart rate and quickly wind down at night.
If you are experiencing sleep deprivation due to stress and anxiety speak to a doctor.
Set a pre-sleep routine
You may follow a ritual like reading a book, eating a fruit, or a warm bath before bed to fall asleep as soon as you hit the bed and lower the risk of hypnic jerks.
Other things to help prepare your brain to sleep as soon as you lie down at night is –
- No screen time 30 minutes before bedtime
- Disconnect from any source of technology
- Mild stretching
- Turn down the lights
- Lower the bedroom temperature
- Sleep on a mattress that suits your body and sleep needs
Yoga or walking or any other moderate-intensity exercises are best for people who prefer to exercise late in the day. Try to finish your workouts at least 90 minutes before bed to slow down your heart rate and prevent twitching in sleep.
Avoid Nicotine and Alcohol
Both nicotine and alcohol hamper your sleep quality which leads to sleep deprivation and a higher risk of hypnic jerks. Minimize the consumption of these substances and look out for healthy alternatives.
Consult your doctor if you cannot resist taking alcohol or nicotine.
Minimize Your Caffeine Consumption
Avoid caffeine consumption later in the day to prevent sleep deprivation and the risk of hypnic jerks. Schedule your last cup of coffee at least 6 hours or more before hitting the bed. Restrict your caffeine intake to not more than 400 milligrams per day. Be aware of sources of caffeine like chocolate.
Hypnic jerks are not a disorder! They are very common and are not associated with serious health complications. Stress and anxiety are one of the main hypnic jerk causes. Again multiple sleep twitches in succession can also trigger anxiety about falling asleep. This vicious cycle can cause sleep deprivation and other health complications. Practice a healthy lifestyle and relaxation techniques for preventing hypnic jerks.
If nothing helps you prevent sleep starts or get a sound sleep at night, consult a doctor immediately.
It is due to a sudden and quick, involuntary muscle contraction that occurs when you are just falling asleep. The twitch occurs mainly during the transition from wakefulness into sleep.
No. if the frequency or intensity of hypnic jerks is high and it’s interfering with sleep onset and causing sleep problems like insomnia, consult your doctor immediately.
Yes, if your hypnic jerks are vigorous.