One of the most common sleeping disorders, and one of the milder ones, is an involuntary muscle spasm or jolt which occurs just as we are falling asleep – a sleep start. This condition is known as a hypnic jerk or hypnagogic jerk. It is a reaction very like the “startle” response and can be accompanied by a falling sensation. It can feel like an electric shock just before dropping off.
Something around 10% of the population will experience hypnic jerks on a regular basis and 60% to 70% at some point in their lives. They often happen if we fall asleep in an uncomfortable position, are sleep deprived or over tired or are having a stressful or anxious time. A hypnic jerk is a type of myoclonic twitch and is similar to a hiccup. It’s considered to be a benign condition.
Not enough research has been done on the subject to give a definitive answer on why they occur but there are a number of theories.
One is that it is just a part of falling asleep in some people. As part of a number of stages from changing brain waves, slowing heartbeat and breathing, the bodies muscular systems transition into their “sleep” state accompanied by the jerk.
Another theory is that as the muscles relax our brain is tricked into thinking that it is falling, drowning or somehow in danger. The jerk is an attempt to turn oneself upright or catch something leading to safety.
Most people experience the hypnic jerk once or twice a night and often don’t even know they are undergoing the reaction. A more severe case can severely affect the sufferers or a bed partners sleep inviolves the twitching every 30 seconds throughout the night. This sleeping disorder is known as periodic limb movements (nocturnal myoclonus).
Generally hypnic jerk requires no treatment and is a normal part of sleep every so often. No “cure” has been developed. A return to normal sleeping patterns, retiring to bed before overtiredness or treatment for the underlying stress and anxiety will often reduce the occurrences another suggestion is to avoid caffeine and spend some time before attempting to fall asleep engaged in relaxation.
If the jolt is causing you more than a mild surpise or is preventing you from getting regular sleep than see you doctor.