You are gently drifting off to sleep when suddenly your arms and legs convulse, jolting you awake. Or perhaps your dozing partner gives an almighty twitch, startling you. This phenomenon is called a hypnic jerk or sleep start, often accompanied by a sensation of falling or tripping. An estimated 70 per cent of people will experience it at some point.
What Causes Hypnic Jerks?
Sleep researchers do not know exactly why hypnic jerks occur, but several theories exist. As the body transitions from wakefulness to sleep, the nervous system winds down and muscles relax. Sometimes, the brain misinterprets this relaxation as a sensation of falling or tripping. In response, the brain sends a quick but powerful signal to the body, resulting in the hypnic jerk.
Hypnic jerks usually affect one side of the body and are painless. However, some people may experience a tingling or painful sensation. For most, these jerks are not associated with health or sleep problems. When they occur frequently over a prolonged period, people may anxiously anticipate them, potentially leading to insomnia.
Links to Health Conditions and Medications
Some research suggests hypnic jerks may be more common in people with conditions such as Parkinson's disease. A 2016 study indicated they could be an early symptom, but this is unlikely without other common symptoms like movement changes or REM sleep behaviour disorder.
Frequent hypnic jerks disrupting sleep can be a side effect of certain prescription medications, particularly antidepressants like selective serotonin reuptake inhibitors (SSRIs), including escitalopram, sertraline, and fluoxetine. Although considered rare, researchers have reported cases where these medications cause hypnic jerks, often resolving after stopping the medication. If concerned, consult your prescribing doctor.
Other medications containing caffeine and non-prescribed stimulants such as cocaine have also been linked to hypnic jerks.
Prevention and Sleep Hygiene
Hypnic jerks are normal and generally no cause for concern. However, lifestyle factors can increase their likelihood. These include:
- Sleep deprivation
- Stress and anxiety
- Excessive intake of stimulants like nicotine or caffeine
- Strenuous exercise before bed
Keeping these factors under control is part of good sleep hygiene, whether or not you are worried about hypnic jerks.
This article is republished from The Conversation under a Creative Commons licence. Read the original article.
