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Have you ever felt the sudden twitch in your body while you were trying to fall asleep? You woke up, and it seemed like you were dreaming about missing a step, slipping, or falling. Your heart rate was increased, and it took you a few minutes to go back to sleep, and sometimes you might even had a hard time meeting the Sandman again. If you have ever experienced this, don’t worry, you are not alone, and it is completely normal.
These events are called sleep starts, or hypnic or hypnagogic jerks, and they are quite common. Almost everybody experiences it at some point in their lives, and they can also affect anybody, no matter your sex, racial background, or age.
Sleep starts are usually harmless, and they don’t require any medical assistance. However, there are some reported cases of hypnic jerk anxiety, where person’s events were so frequent and unpleasant, that they developed a negative attitude towards going to sleep. Sometimes, sleep starts can be a sign of some underlying sleep or a mental disorder.
Hypnic jerks are a part of a wider variety of involuntary movements called myoclonus. Sleep starts are not considered a sleep disorder, and they usually don’t require any treatment. There are some things you can try to lower the chances of these events if you experience them frequently or they feel startled by them.
What is Myoclonus?
Myoclonus refers to a sudden twitching of muscles. If sudden muscle contractions cause it, it is called positive myoclonus, and in case of muscle relaxation it is negative myoclonus. They can be single events, or they could happen in a sentence or a specific pattern.
Besides sleep starts, hiccups are another excellent example of myoclonus. While these are entirely harmless, severe cases of myoclonus affect a person’s ability to move, eat, or talk. Those are often a sign of some underlying condition, or brain and nerve damage, and need to be treated.
Myoclonus can develop as a result of head or spine injury, infections, liver or kidney failure, brain tumors, drug poisoning. Myoclonic jerks can also occur in patients who have multiple sclerosis, Alzheimer’s disease, Parkinson’s disease. They are frequent in people with epilepsy because the brain’s electrical signals are distorted.
Types of Myoclonus
There are some forms of myoclonus; here we listed the ones described by the National Institute of Neurological Disorders and Stroke (NINDS):
- Action myoclonus is characterized by the jerks when making a voluntary movement, or even thinking about it. It can affect legs, arms, face, even the voice. It is one of the more disabling types of myoclonus, and it’s usually caused by the nerve damage that is due to the lack of blood flow and oxygen delivered to the brain.
- Cortical reflex myoclonus is typically triggered by a specific action, just like action myoclonus, or it can be due to some sensation.
- Essential myoclonus is not caused by the abnormalities in nerves and brain, and the cause is still unknown. It usually occurs in the same families, hinting that it may be possible to inherit it. It seems stable over time, and people who are experiencing it are not reporting the increase of symptoms severity.
- Palatal myoclonus is a contraction of the soft palate, a back end of your mouth, and happens regularly. These may be accompanied by jerks in other parts of face, tongue, throat, or diaphragm. This condition mostly affects adults, and the contractions can be very rapid, as many as 150 per minute. It mostly happens at night, and for most of the people, it’s a minor problem, while others hear a clicking sound in their ears, or report pain and discomfort.
- Progressive myoclonus epilepsy (PME) refers to a group of disorders with symptoms like myoclonus, trouble walking or speaking, epileptic seizure, and other severe symptoms. There are many forms of PME. They usually begin in childhood, and get worse over time, with sometimes fatal outcome. Luckily, these disorders are extremely rare.
- Reticular reflex myoclonus is a type of generalized epilepsy that is correlated with the brain stem, a part of the brain responsible for vital functions like heart and breathing rate. These jerks usually happen in the whole body, but there are some cases where they affect only a part of the body, like the legs. They occur on both sides at the same time, and jerking involves all muscles in that body part. Reticular reflex myoclonus occurs voluntary movement or due to some some external stimulus.
- Stimulus-sensitive myoclonus as the name says, is caused by external stimuli like noise, movement, and light. Not expecting the stimuli may increase the chances of jerks appearances.
- Sleep myoclonus mostly occurs in the first stages of sleep, most likely at the very beginning. Some cases report that the external stimuli can trigger it. While mostly harmless, it can sometimes be a sign of a sleep disorder such as restless legs syndrome, and it may require medical treatment.
Why Do Hypnic Jerks Occur?
It is still unclear why do sleep starts happen, and researchers are trying to figure that out. It is most likely due to misfiring of neurons when some parts of the brain fall asleep faster than the others. Another interesting hypothesis says that hypnic jerks are an ancient primate reflex. They supposedly happen because of the relaxation that is sometimes misinterpreted as a falling out of the nest in the trees, so twitching happens to wake us up.
Whatever the cause, they are thought to affect most of the population, and they are more frequent in young children. Some risk factors are shown to increase the chances of sleep starts occurring. High intake of the caffeine and other stimulants, especially too close to bedtime may set it off. Emotional trauma, stress, poor sleeping habits, and high-intensity exercise before sleep are common triggers as well. Medication abuse, iron deficiency, and urea build up are also suspects for potential causes. Certain sleep disorders like obstructive sleep apnea can play a role too. Frequent unpleasant episodes of sleep starts need a medical examination, as they can lead to anxiety and sleep onset insomnia, or they can be a sign of a more complex underlying problem.
Other causes of sleep movements include:
- Restless legs syndrome is described by the uncomfortable feeling in the legs when resting, with an urge to move them and relieve the pain.
- Periodic limb movement disorder occurs during sleep, and it is described by the periodic rhythmic contraction and relaxation of the muscles. Unlike hypnic jerks, these are not single events.
- Shivering while sleeping in a cold environment can cause nocturnal movements as well. It affects the whole body and can be resolved by warming up or treating the fewer that is causing it.
- Fasciculations happen in a specific muscle or group of muscles. It appears as quivering, they are more persistent than hypnic jerks, and can occur during wakefulness.
How to Deal With Sleep Starts
In most cases, hypnic jerks can be improved through changing lifestyle habits like:
- Avoiding high-intensity exercise before bed. Although regular physical activity is one of the best ways to get better quality sleep, it seems that exercising too close to bedtime can be counterproductive and increase the chances of sleep starts.
- Avoiding caffeine. Caffeine is a stimulant, and it is found in coffee, tea, chocolate, and many other things. It helps us get alert in the morning, but having it later in the day might affect our sleep quality.
- Avoiding other stimulants. Alcohol and nicotine can lead to disrupted sleep and hypnic jerks, especially if taken close to bedtime.
- Creating a relaxing bedtime routine. It is essential that you unwind before bed as it will help you fall asleep faster, and stay sound asleep during the night. Different things work for different people, so you might try reading, taking a hot bath, drinking caffeine-free tea or a warm glass of milk, listening to mellow music, meditating, breathing exercises, light yoga, taking a hobby, or any other thing that helps you relax.
- Creating a pleasant sleep environment. Your bedroom should be dark, quiet, fresh, and free of screens and distractions. Also, try to stick to a regular sleep schedule, where you’re going to sleep and waking up at the same time every day.
If your symptoms are persistent, and these sleeping tips don’t help you, you should consult a medical professional. They may need to do an overnight sleep study called a polysomnogram, where they will observe your brain waves, respiration and heart rate, and many other things. That way they can determine what is causing your sleep problems and prescribe the right treatment. Sleep starts can be treated with leg exercise, iron supplements, dopamine agonists in really bad cases, as well as other medical supplements.
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Dusan is a biologist, a science enthusiast and a huge nature lover. He loves to keep up to date with all the new research and write accurate science-based articles. When he’s not writing or reading, you can find him in the kitchen, trying out new delicious recipes; out in the wild, enjoying the nature or sleeping in his bed.