Hypnagogic jerks refer to involuntary bodily twitches, movements, or muscular jolts that occur during the transition from wakefulness to a sleeping state. Most people are thought to experience them just moments before entering the first stage of sleep. In some cases, hypnagogic jerks are also referred to as “sleep twitches” or “sleep starts,” but are sometimes referenced as “hypnic jerks,” which is a broader term characterizing jolts occurring at any point throughout the night.
Perhaps you’ve experienced a hypnagogic jerk as you attempt to fall asleep. You may lie down for bed, feel as if you’re on the brink of sleep, and suddenly your body jolts involuntarily. There’s nothing you can do about the jerks, but they usually subside quickly and before you know it, you’re fully asleep.
Even if you’re unaware of these sensations, your partner may notice that you unexpectedly twitch before falling asleep. Your partner may be alarmed by the sudden jolt, and worry that something more serious is occurring. Although these sensations aren’t considered harmful, they are commonly associated with frequent fluctuations in your sleep schedule.
What are hypnagogic jerks? Definition.
Hypnagogic: This is a term comprised of the Greek derivatives “hypnos” which refers to sleep, and “agōgos” which refers to preceding (or coming before). It signifies the state of consciousness just before we fall asleep. In other words, the time when we aren’t fully awake, but aren’t quite asleep is the hypnagogic state.
Jerks: This refers to sudden (possibly unexpected) bodily movements or jolts. In most cases a jerk is an involuntary, unconscious reaction to threatening stimuli. Anytime you make a sudden, quick, or sharp movement – this is considered a jerk.
Hypnagogic jerks: Combining the terms hypnagogic and jerks, we are left with the term hypnagogic jerk, which signifies sharp, unexpected bodily movements (or jolts) during the transitory consciousness of wakefulness to sleep.
The jerks experienced during a hypnagogic state may resemble a flinch, shock, or instantaneous reaction. Think of how people react when they accidentally put their hand on a hot stove – the reaction isn’t a result of the conscious part of the brain, it’s an instinctual innate reaction from the unconscious.
Possible causes of hypnagogic jerks
It is difficult to pinpoint the specific causes and mechanisms of hypnagogic jerks. There are many theories as to why these hypnagogic jerks occur, but none have been universally confirmed. Therefore it should be speculated that the specific causes and mechanisms may be subject to subtle individual variation.
“Abort sleep” mechanism: Some speculate that hypnagogic jerks are a mechanism that allows your brain to decide whether it truly wants to sleep, or whether it should remain alert and wake up. Without the jerk, you would drift off into a sleeping state without having the option of remaining awake. When hypnagogic jerks are experienced, they may be the result of your brain deciding to abort sleep, which triggers your peripheral nerves (in arms, legs, etc.) to fire (or misfire) and a powerful jolt ensues – keeping you awake.
Evolutionary reflex: Many theories regarding the specific cause of hypnagogic jerks are related to human evolution. The one thing that these evolutionary theories agree on is that hypnagogic jerks were a result of an innate response engineered to increase survival of the organism.
- Falling: One evolutionary theory for these jerks upon sleep onset is that as you relax before sleep, the brain may interprets the relaxation as a sign that you’re about to fall out of a tree. From this perspective, a primate may have gotten comfortable in a tree, was on the verge of sleeping, but the brain produced an involuntary jolt to keep the primate alert (rather than sleep) and thus prevent falling.
- Predators: The hypnagogic jerks may serve as a reminder to double-check your environment for potential predators prior to sleeping. This characteristic may have gotten passed on through evolution because primates that “jerked” may have been better at fending off predators and/or had greater success at evading predatory attacks that may have occurred during sleep. Think of it as a safety protocol from your brain asking, “Are you sure you want to sleep? There may be hyenas lurking.”
- Psychological priming: Some have speculated that the hypnagogic jerks may serve as an evolutionary reminder to make sure that we’ve finished everything we needed to for the day. In other words, did we gather sufficient food, find a safe shelter, and complete all of the tasks we wanted to complete. This could be interpreted as a psychological priming mechanism that reminds us to stay awake if we aren’t quite finished with necessary survival-related tasks.
It is important to consider the fact that theorized specifics may differ for each person. Although the underlying purpose may have been to initially keep the organism alive, the purpose for the jerking may have changed over time.
Limbs preparing for REM: Another idea is that as you transition from wakefulness to a sleeping state, your brain shuts down and prepares for REM (rapid-eye movement) activity. Upon preparation, your brain may shut down activation of limb control for REM. This is why sleep paralysis occurs during REM – your limbs become temporarily paralyzed to prevent you from acting out your dreams.
As the brain prepares for REM by deactivating voluntary motor control, hypnagogic jerks may occur as a result of this transition. They may occur as a result of abnormal brain activity during this transition, or they may occur as a natural byproduct of this transition. Inevitably, REM-atonia ensues, thus preventing you from moving your muscles during sleep.
Nerve misfiring: One hypothesis for the hypnagogic jerks is that they are an inherent aspect of the body’s transition from wakefulness to sleep. This hypothesis suggests that as we transition to a sleeping state, our nerves may occasionally misfire, causing a jolting movement immediately before we’re fully asleep. Since hypnagogic jerks do not always occur for everyone each night, it may be a sign that nerves do not always misfire during the wakefulness to sleep transition.
Some have compared this to the brain shifting gears on a manual transmission. It is slowing from a state of wakefulness to a sleeping state. It’s attempting to shut itself down, which during this transition, there may be some “jolting” as a result of a rockier-than-usual transition.
Non-REM (NREM): Another idea is that hypnagogic jerks occur during the non-REM (rapid-eye movement) portion of sleep. During this non-REM portion of sleep, it is thought that arousal may occur, particularly with the illusion of falling. Additionally, abrupt muscle action flexing movements may occur that have been reported as asymmetrical, partial, and/or symmetrical.
Stimulation of reflex: A theory that I have is that hypnagogic jerks are the result of reflex stimulation, possibly from bursts of brain activity. These bursts of brain activity may then trigger regions of the brain involved in motor control, resulting in a brief twitch corresponding with the “burst.” The stimulation of reflex could also be triggered by REM-like activity leading to a dream or dream-like state before muscular control is fully inhibited as a result of REM-atonia.
The dream-like state that we experience could trigger a movement related memory or image, and lead to a reflexive response. An example would be a person on the brink of sleeping, experiencing hypnagogic or dream-like activity involving movement, and the movement stimulates the a reflex response from the motor cortex, which produces a “jerk.”
Sleep spindles: Many individuals believe that hypnagogic jerks are a result of sleep spindles. These refer to bursts of brain waves generated by the reticular nucleus region from the thalamus. They occur during Stage 2 sleep and are documented as being between 12 and 14 Hz (beta waves).
A specific type of sleep spindle known as the “K-complex” occurs during NREM sleep and has been thought to provoke hypnagogic jerks. The functions of K-complex spindles are: to decrease cortical arousal for sleep when danger is ruled out, and to enhance memory consolidation.
- Source: http://link.springer.com/article/10.1007%2Fs007020300001
- Source: http://www.ncbi.nlm.nih.gov/pubmed/24815789
- Source: http://www.ncbi.nlm.nih.gov/pubmed/23912581
Factors that may contribute hypnagogic jerks
While the underlying neurological activation may be similar among those experiencing these sleep-onset jerks, the contributing factors may be subject to significant individual variation. For one person the cause may be frequent alterations in sleep cycle, yet for another the cause may be from a pharmaceutical medication.
Anxiety: Those with anxiety disorders or acute, pent-up anxiety may be more prone to hypnagogic jerks. It isn’t known exactly why individuals with anxiety may experience these “sleep twitches” at greater rates than others, but some believe it may be due to activation of the sympathetic nervous system or transitional abnormalities between intense fearful alertness and sleep. Anxiety disorders are linked to a variety of sleep problems and abnormalities including: insomnia, circadian rhythm disruptions, decreased sleep length, and poorer sleep quality.
Brain lesions: Some research shows that hypnagogic jerks may be more likely among those with brain lesions. Among individuals with neurological conditions, lesions to the pyramidal tract of the brain may lead to increased rates of hypnagogic jerks. Researchers believe that lesions to this particular region may result in uninhibited motor movements upon sleep onset.
The brains of individuals without lesions are more likely to inhibit the motor systems (pyramidal tract) of the brain as we transition to sleep. Those with lesions to this particular area may be unable to inhibit the motor systems as a result of the injury or damage.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/10937135
Caffeine consumption: While all stimulants could be considered factors that may influence the likelihood of hypnagogic jerks, caffeine is the most popular and should be discussed. Some sleep experts believe that those drinking large quantities of coffee may impair their sleep schedule, quantity, and quality. Additionally drinking caffeine in the afternoon may disrupt the circadian rhythm – which could factor in towards increasing likelihood of hypnagogic jerks.
Drugs and alcohol: Using any drugs or drinking alcohol should be considered as a potential factor that increase risk of experiencing twitches upon sleep onset. It is known that drugs and alcohol are capable of altering natural neural processes, thus it is possible that interruptions to those processes affect transition between wakefulness and sleep. The disruption as a result of drinking or drug usage may increase occurrences of these jerks.
Exercise: Someone who exercises frequently may experience an increased amount of hypnagogic twitches as a result. Exercise may exhaust a person physically and mentally, leading to decreased energy stores and changes in brain activation. If intense exercise is performed in the afternoon or evening, it may disrupt your brain’s ability to transition into a sleeping state.
Disruptions in the transition may create neural activation abnormalities that cause the jerks to occur. Additionally, those that exercise may have primed their “motor cortex” involved in movement, and when winding down for sleep, the cortex may “fire” or “misfire” as a result of frequent or intense earlier stimulation, leading to the jerk.
Sleep disorders: Those with sleep disorders, particularly if they are untreated, may experience hypnagogic jerks as a result of abnormal brain activity related to the disorder. As an example, it is known that individuals with narcolepsy experience a variety of sleep related phenomena (e.g. hallucinations, paralysis, etc.) than those with normative sleep patterns. Sleep disorders may contribute to neurotransmitter changes, EEG alterations, and increase susceptibility to hypnagogic jerks.
Sleep variables: It is important to consider that sleep variables may factor into provoking a hypnagogic jerk. These variables include things like: sleeping position, sleep quality, sleep quantity, and variation in sleep schedule.
- Deprivation: Those who are sleep deprived or have restricted sleep for a long period of time are thought to exhibit more sleep-related problems. Prolonged sleep restriction should be considered as a variable that may increase likelihood of hypnagogic jerks.
- Position: It is important to consider that sleep position may affect the frequency by which a person experiences hypnagogic jerks. Those sleeping on their back (i.e. supine position) are more prone to sleep related phenomena, and thus may be more prone to these jerks.
- Schedule: A highly variable sleep schedule may increase risk for circadian rhythm disruptions and ultimately produce more sleep related phenomena, including hypnagogic jerks. Those with an inconsistent sleep schedule may jump into full REM or experience abnormal transitioning between sleep phases, leading to jerks in hypnagogic states.
Stimulants: Those that use stimulatory agents, regardless of whether they are over-the-counter, pharmaceutical, or illicit may experience more hypnagogic jerks than average. The stimulation from these agents may affect neurotransmitter levels, physiological functioning, and regional activation of the brain.
When stimulants are used, especially in the latter parts of the day (e.g. afternoon), they may disrupt a person’s ability to fall asleep. This could result in a circadian rhythm disruption, different EEG activity, and possibly hypnagogic hallucinations. In many cases, hypnagogic jerks may be a byproduct of a stimulant-induced cascade of changes.
Stress: Those experiencing acute or long-term (cumulative) stress may be more prone to hypnagogic jerks. Stress can alter the brain’s natural ability to downshift from conscious awareness and worrying (beta waves) to subconscious, slower activity (alpha waves) before bed. It could be thought that problems with the brain’s ability to “downshift” as a result of stress may result in sleep abnormalities and increase incidences of hypnagogic jerks.
Hypnagogic Jerk Treatment
Since hypnagogic jerks aren’t considered a harmful condition, there’s no official medical treatment. That said, treating conditions that may contribute to the jerks (e.g. sleep disorders) may decrease their occurrence. Various potential treatments include: positional adjustments, pharmaceuticals, elimination of stimulants, and a regimented sleep schedule.
- Alter sleep position: Some people may have success in altering their sleep position from “supine” (on the back) to sleeping on the side or stomach. Sleeping on the back has been associated with a variety of odd sleep experiences and phenomena. It should be theorized that altering your sleep position may decrease likelihood of hypnagogic jerks.
- Bed firmness: It should be considered that a more firm or less firm bed may influence brain activity prior to falling asleep. Those on a less firm bed may receive less muscular stimulation and thus feel as if they are falling or floating, which causes a jerk. Similarly those with extremely firm sleeping surfaces may end up with overstimulated musculature, leading to nerve misfirings and provoking a reflexive startle “twitch.”
- Brainwave alterations: Due to the fact that one theory is that hypnagogic jerks are caused by bursts of brainwave activity, you could consider using various types of brainwave entrainment to change pre-sleep brain waves. Entrainment to a slower brainwave state such as alpha or theta may allow for a smoother transition from wakefulness to sleep, and decrease abnormal brainwave activity that may produce “jerks.”
- Cut drugs and alcohol: If you believe that drugs and/or alcohol are causing the hypnagogic jerks, you may want to either decrease consumption and/or quit using them. Obviously if you’re taking a pharmaceutical agent, you may not be able to discontinue, but you should realize that it could be indirectly contributing to the jerks that you’re experiencing. Discontinuing caffeine and/or alcohol may help decrease hypnagogic jerks.
- Decrease nighttime activity: If you’re involved in physical activity in the afternoon or at night, this may lead to an overactivation of the motor cortex. Just before bed, your brain may have a difficult time shutting down, and in particular turning off this region. Upon attempt to deactivate this region for sleep, you may jolt during the process. If you find yourself working out later in the day, playing sports at night, or engaging in activities requiring fine motor skills – these could increase likelihood of hypnagogic jerks.
- Eliminate stimulants: Although it was recommended to eliminate drugs and/or alcohol, you may need to focus more on eliminating all stimulatory agents. Regardless of whether the stimulant is a pharmaceutical drug or legal drug like caffeine, these agents may increase likelihood of hypnagogic jerks. If you want to decrease the jerks, you may want to reduce, eliminate or consume stimulants only within specific windows of time (e.g. the early morning).
- Pharmaceutical drugs or supplements: In some cases, taking a pharmaceutical drug to help with sleep quality may simultaneously reduce or eliminate hypnagogic jerks from your life. In other cases, taking the right supplements may result in a similar effect. If you need medication for your sleep or a supplement (e.g. melatonin), you may find that they decrease the jerking.
- Regimented sleep schedule: By sticking with a regimented or strict sleep schedule, your circadian rhythm should adapt. Those with variable sleep schedules may have a circadian rhythm that isn’t aligned with their sleep schedule, thus resulting in all types of physiological chaos. Decreasing this physiological chaos with a good sleep schedule may also reduce the jerks.
- Treat underlying condition: If you have an underlying neurological condition, sleep disorder, or medical condition, proper treatment may decrease the occurrence of hypnagogic jerks. Failure to treat a condition such as a neurodegenerative disease may result in abnormal brain activation at night when it’s time to fall asleep. This abnormal activation may lead to jerks being experienced before bed.
Frequently asked questions (FAQs)
Below is a list of frequently asked questions related to hypnagogic jerks. If you have an additional question that you’d like answered, feel free to submit it in the comments section below.
Is there a cure for hypnagogic jerks?
There is no “cure” for hypnagogic jerks. In some cases they occur naturally in healthy people and regardless of strategic sleep-related adjustments, they persist. That said, many people have noticed that when they decrease consumption of stimulants, adhere to a strict sleep schedule, and decrease strenuous physical activity (or activities involving fine motor skills) in the evening, the hypnagogic jerks may subside.
What’s the difference between hypnagogic jerks and hypnic jerks?
Hypnagogic jerks refer to uncontrollable jolts that occur prior to being fully asleep. Hypnic jerks refer to any uncontrollable jolts that occur during or around sleep. In other words, a hypnagogic jerk is a specific subtype of the (broader classified) hypnic jerk.
Are hypnagogic jerks a sign of epileptic seizures?
Hypnagogic jerks (or sleep starts) aren’t a classified as a sign of epilepsy or seizures. While they may appear to be similar to myoclonic jerks as a result of epilepsy, it is necessary for medical professionals to distinguish one from the other. Hypnagogic jerks only occur upon sleep onset, whereas myoclonic jerks associated with epilepsy can occur anytime throughout the day.
Who is most likely to experience a hypnagogic jerk?
It is estimated that over 60% of the entire population experiences hypnic jerks. A majority of these jerks are likely hypnagogic (occurring prior to sleep). Others may not report them or they may remain unnoticed as a result of the person being nearly asleep. Individuals with medical conditions, sleep disorders, and abnormal sleep schedules may be more at risk than average.
Personal experience with hypnagogic jerks
In the past I may have experienced hypnagogic jerks and didn’t know it, but they’ve only come to my awareness within the past couple years as a result of my girlfriend quickly pointing them out. She says that my arms “twitch” or “jolt” right before I’m about to fall asleep. She elaborated by thinking I was going to have a seizure during my sleep, which isn’t the case.
Sometimes I’m subtly aware of the jolt, possibly still have just enough beta wave activity to detect myself jolting. In other cases, I may be nearly unconscious and do not detect the jerks occurring. I have noted that sometimes the hypnagogic jerks are primed with visuals – perhaps from REM-like activity.
In other words, I’ll be half-dreaming in a hypnagogic state and envisioning some physical activity such as catching a baseball or reacting to a punch, and out of nowhere, I jolt and become aware of it. In this case I wasn’t fully asleep, even though I had been experiencing dream-like visuals in hypnagogia. This motion-based visuals may stimulate the motor cortex to act out the motion and thus produce a jerk.
I suspect that caffeine consumption in the afternoon, athletic activities at night (involving fine-motor skills), and sleep schedule may play a role in causing these jerks, but it’s tough to be sure. I have noticed that when I take naps as a result of poor sleep quality or quantity the previous night, that I may experience them prior to becoming fully asleep in the nap. While the jolts are sometimes unsettling, they don’t occur every night and aren’t really a concern.
Have you ever experienced a hypnagogic jerk?
If you’ve experience sudden jolts of movement upon sleep onset, feel free to post a comment about them below. You may want to mention how frequently you experience them, any factors that you believe contribute to them (e.g. shift work), and the specific part (or parts) of your body that most often jerk. Understand that hypnagogic jerks are those occurring during the transition from wakefulness to sleep, not the jerks that occur at any juncture of the night – those are “hypnic jerks.”