Dr Amir Khan, a regular health contributor on ITV's Good Morning Britain and Lorraine, has addressed a common sleep phenomenon: the sudden jolt or falling sensation that occurs just as one drifts off. In a TikTok video, he explained that this involuntary muscle spasm is known as a hypnic jerk.
What Causes Hypnic Jerks?
According to Dr Khan, as you transition into sleep, your muscles relax. The brain sometimes misinterprets this relaxation as falling and sends a quick signal to the body to catch itself, resulting in a twitch that wakes you. He noted that some scientists believe this is an ancient survival reflex from when humans slept in trees, where a sudden twitch might prevent an actual fall.
Dr Khan emphasised that hypnic jerks are totally harmless and more common when you are stressed, have consumed caffeine late, or are extremely tired. He reassured viewers: "It's totally normal, totally harmless. So next time it happens, don't panic. It's just your brain being quirky."
Prevalence and Scientific Explanation
The Sleep Foundation reports that 70% of people experience hypnic jerks at some point. The organisation describes them as abrupt, involuntary muscle spasms that often feel like a jolt, a falling sensation, or a sudden kick. These movements typically affect one side of the body, such as an arm or leg, and may be accompanied by a brief dream or startled feeling.
Researchers are not certain about the exact cause, but theories suggest that hypnic jerks originate in the same part of the brain that controls the startle response. A misfire between nerves in the reticular brainstem during sleep onset may create a reaction leading to the jerk. Alternatively, when muscles relax completely, the brain may mistakenly assume falling and trigger a muscle twitch.
Tips to Reduce Hypnic Jerks
The Sleep Foundation recommends several measures that may reduce the frequency of hypnic jerks:
- Going to bed and waking up at the same time every day
- Keeping the bedroom between 18 and 20 degrees Celsius
- Making the bedroom as dark and quiet as possible
- Avoiding electronics at least one hour before bed
- Reducing stress through yoga, meditation, reading, or a warm bath
- Exercising daily, but not late in the evening
- Limiting caffeine, nicotine, and alcohol consumption
