Have you ever been drifting off into a peaceful slumber when, out of nowhere, your body jerks, and suddenly, you’re wide awake with a racing heart, wondering what happened?
This bizarre phenomenon is known as a hypnic jerk, and it’s surprisingly common.
Hypnic jerks, also referred to as sleep starts or sleep jerks, are a form of involuntary rapid muscle movement known as myoclonus.
We’ve all experienced myoclonus before in the form of hiccups. Though hiccups can be annoying, contrarily, hypnic jerks can be downright shocking and even scary. They hit when we’re least expecting it, and they’re often accompanied by dream-like visuals and the feeling of falling.
If this scenario sounds familiar, don’t worry, you’re not alone. According to Elsevier’s Sleep Medicine Journal, 70% of people experience hypnic jerks every now and then. But what are they, and why do they occur?
In this post, I’ll explain what science has to say about hypnic jerks, including what causes them and what you can do to reduce their frequency, so you can get a better night’s sleep.
Hypnic Jerks Explained
Hypnic jerks are a common natural phenomenon and most often not considered to be a serious disorder. They’re simply a natural muscle contraction that occurs when our bodies are in a state of hypnagogia, hence the term hypnic.
As well as making us feel like we’re falling, these unexpected jerks paired with hallucinations are usually like bright flashing lights and a loud bang or crash.
But not all hypnic jerks are startling enough to wake us up from our slumber. Often, they’re so mild that we don’t even notice them at all.
Hypnic jerks occur seemingly at random, and while most of the time, they’re an isolated event, in some cases, they can happen in multiple succession.
Muscle contractions usually affect just one side of your body, for example, the right shoulder, arm, and leg. But when you wake up with the sensation that you’ve just fallen off the side of a cliff, it can feel like a whole-body experience.
The Cause of Hypnic Jerks
Scientists are still unsure exactly why hypnic jerks occur, and there’s no universally agreed theory.
Many researchers believe the cause is a misfire in a set of interconnected nuclei called the reticular brainstem. This area of the brain connects our vital bodily functions, such as heartbeat and breath, to the spinal cord.
Interestingly, some scientists theorize that this misfire could be due to an innate evolutionary survival instinct. As you fall asleep, your muscles enter a state of deep relaxation, which the brain could perceive as falling.
And the dream-like imagery or hallucinations that often accompany a hypnic jerk could actually be the original trigger of the involuntary muscle contraction.
In other words, these spontaneous sleep twitches could have been the brain’s way of waking up our primate ancestors to keep them safe.
University of Colorado psychologist, Frederick Coolidge, agrees. He suggests that hypnic jerks could be “an archaic reflex to the brain’s misinterpreting the muscle relaxation accompanying the onset of sleep as a signal that the sleeping primate is falling out of a tree. The reflex may also have had selective value by having the sleeper readjust or review his or her sleeping position in a nest or on a branch in order to assure that a fall did not occur.”
But other researchers have come to a different conclusion. Some theorize that hypnic jerks are actually our brains performing a test to see if we’ve reached the REM sleep stage.
While in REM, our bodies enter a form of muscle paralysis called muscle atonia that stops us from acting out in dreams. Hypnic jerks tend to occur in earlier, non-REM sleep stages; our limbs respond with jolting muscle contractions that can be profound enough to startle us out of our slumber.
So, it seems that the hypnic jerk phenomenon is still something of a scientific mystery, but one thing researchers do agree on is their potential triggers.
Several risk factors can increase the chances of hypnic jerks occurring as you fall asleep, including the following…
Sleep deprivation disrupts the brain’s natural transition between a wakeful state and a sleep state, known as hypnagogia. If you suffer from insomnia, your chances of experiencing hypnic jerks increase. This can lead to more frequent triggers of these startling muscle contractions.
Those who suffer from disturbed sleep also typically spend longer in hypnagogia and less time in a deeper sleep, so hypnic jerks are more likely to be a regular occurrence.
2. Stress & Anxiety
Stress and anxiety can lead to bouts of insomnia or disturbed sleep, so for the same reasons above, these emotional states can increase the likelihood of hypnic jerks.
Additionally, stress elevates levels of the steroid hormone cortisol. Cortisol is known to trigger misfires in the sympathetic nervous system, which can manifest as hypnic jerks.
Common stimulants such as caffeine and nicotine make it harder to fall asleep, increasing your chances of sleep deprivation and insomnia.
These everyday substances stay in our systems for several hours after they’re consumed. So, even if you had your last cup of coffee in the middle of the afternoon, it can still disrupt your sleep and trigger hypnic jerks when you do eventually drift off.
Alcohol is a depressant, but just like stimulants, it can disrupt your usual sleep patterns and alter your circadian rhythm, resulting in an increase in hypnic jerks.
5. Exercising Before Sleep
Generally speaking, regular, vigorous exercise is a fantastic tool to help improve your quality of sleep.
Moreover, timing is important, and hitting the gym, going for a run, or lifting weights too close to bedtime will leave you feeling energized and alert. This will disrupt your circadian rhythm, making it much harder to fall asleep. And as a result, the likelihood of experiencing a hypnic jerk increases.
6. Low Levels of Magnesium
Magnesium is an essential mineral that keeps our bodies running as they should. One of its functions is regulating muscle contractions, and so, in some cases, hypnic jerks can be a warning sign of a magnesium deficiency.
How to Prevent Hypnic Jerks?
If you’re experiencing frequent hypnic jerks and it’s causing you concern, speak to your doctor. While occasional hypnic jerks are a normal part of sleep, frequent episodes could indicate an underlying condition.
But if your doctor has given you a clean bill of health, and you’re looking for some simple and effective ways to prevent hypnic jerks from disturbing your slumber, then there are a few things you can do.
To begin with, start by addressing the triggers listed above. Avoid substances like coffee, nicotine, and alcohol, and try to plan your workouts earlier in the day so that you don’t get a boost of energy right before it’s time to go to bed.
If insomnia, stress, or anxiety is present in your life, seek help from your doctor and try to address the underlying cause. And if you suspect a magnesium deficiency may be to blame, get your vitamin levels checked, and if necessary, implement dietary changes and supplements to boost you back into the optimum range.
Practice Healthy Sleep Hygiene Habits
Hypnic jerks are more prevalent when our sleep cycles are disturbed. So, by adopting some better sleep habits, you can reduce hypnic jerks and get the best night’s sleep possible.
So, here are a few other things to try.
1. Limit Screen Time
Blue light from cell phones, laptops, and tablets alters the body’s circadian rhythm and makes it much harder to fall asleep at night. So, try to eliminate all blue light-Emitting Devices for at least an hour before bed.
2. Turn off The TV
Sitting in front of the television before you go to bed can overstimulate your mind and make it much harder to fall asleep.
Even though most television sets don’t emit the same blue light as our handheld devices, the glow of the screen still disrupts our circadian rhythms and reduces the amount of melatonin produced by the body. This makes it harder to fall asleep, and you’re more likely to experience hypnic jerks as you drift off.
3. Keep Your Bedroom Cool
The temperature of your sleep environment can play a huge role in the regulation of melatonin levels and keeping our circadian rhythms in check.
Research suggests that the ideal temperature range for most adult bedrooms is between 60-67°F (15-19° C). Sticking to this pleasantly cool range will help you drift off peacefully and reduce the chances of hypnic jerks.
4. Set a Sleep Schedule And Stick to it
People who go to bed at the same time each night and wake up at the same time each morning are generally better rested. They are less likely to suffer from insomnia or other sleep disturbances, including hypnic jerks.
If your current sleep schedule is erratic, it can be difficult at first. However, after a few weeks, your body will adjust to your new consistent sleep pattern, and you’ll find yourself naturally feeling more tired and drowsy as you go to bed.
Hypnic jerks are a normal part of most people’s sleep, but they can still cause alarm when you’re drifting off into a peaceful slumber.
But the good news is that there are things you can do to reduce their frequency. Most of these strategies center around improving your sleep hygiene and creating healthy bedtime habits. It not only helps to stop those pesky hypnic jerks but also leaves you feeling happier, healthier, and better-rested.