You’re just about to fall asleep, and suddenly it feels like you’re falling, causing you to jerk awake. This sudden jolt, known as a sleep start or hypnic jerk, can be unsettling and disrupt your path to a peaceful night’s rest. It’s a common experience, but what exactly causes these nighttime twitches?
According to experts, experiencing these sleep twitches is surprisingly normal. Dr. William Kohler, Medical Director of the Florida Sleep Institute, notes that as many as 70 percent of people will experience these hypnic jerks as they drift off to sleep. James K. Walsh, Executive Director at St. Luke’s Sleep Medicine and Research Center, emphasizes their commonality, stating, “A hypnic jerk or sleep starts are a perfectly normal occurrence that is almost universal.”
These twitches are characterized by a brief, full-body sensation. “It involves a total body experience where your muscle contracts therefore your limbs jerk or your body twitches,” Walsh explains. These events are fleeting, typically lasting no more than a half-second, and occur during the transition from wakefulness to sleep.
What are Hypnic Jerks?
Hypnic jerks are classified as myoclonus twitches, which are essentially involuntary muscle spasms. These sleep starts specifically happen during hypnagogia, the initial stage of falling asleep. While the majority of people have experienced these jerks, it’s worth noting a rarer, more alarming phenomenon known as exploding head syndrome. This condition involves the sensation of loud noises, like explosions or crashing sounds, occurring as one falls asleep. Despite its frightening name, and the distress it causes, experts like Walsh and Kohler reassure that exploding head syndrome, while unpleasant, is also considered normal and not indicative of a serious physical or mental health issue. “They’re healthy people with a very unpleasant experience,” Walsh clarifies.
The Role of Sleep Stages in Twitches
Movement is intrinsically linked to sleep. Involuntary twitches are also common during rapid eye movement (REM) sleep, the stage associated with dreaming. However, hypnic jerks are distinct as they occur before dreams begin, during the process of falling asleep, not during REM sleep itself.
Unraveling the Mystery: Why Do Sleep Twitches Happen?
The precise cause of hypnic jerks remains unclear, and research is limited due to their harmless and transient nature. However, sleep experts have several theories. Dr. Kohler suggests potential links to “anxiety and stress or with unusual or irregular sleep schedules.”
One prominent theory, shared by Walsh and others in sleep medicine, is that hypnic jerks may be related to mini-REM-like periods that occur as the body transitions into sleep. During this phase, muscles begin to relax, and dream-like sensations might start to emerge. The brainwaves present during hypnagogia do bear resemblance to those seen during REM sleep. This similarity could explain the physiological events that contribute to twitches. During REM sleep, our heart rate, breathing, and nervous system can behave erratically. If the body experiences brief flashes of REM-like activity as it enters sleep, these irregularities might trigger muscle twitches. The general consensus is that hypnic jerks often arise as the body begins to relax and shut down for sleep.
When Should You Be Concerned About Sleep Twitches?
While the sensation of suddenly falling can be alarming, most people do not experience hypnic jerks frequently enough to warrant medical attention. However, if these sleep starts are disrupting your sleep and preventing you from getting adequate rest, Dr. Kohler advises consulting a sleep medicine doctor.
Improving Sleep and Potentially Reducing Twitches
Fortunately, improving your overall sleep routine can be beneficial. Kohler recommends establishing a relaxing pre-bedtime routine, avoiding stimulants like food, smoking, and caffeine close to sleep, and maintaining a consistent sleep schedule by going to bed and waking up around the same time each day. These sleep hygiene practices can contribute to more restful nights and potentially minimize the occurrence of sleep twitches.
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