Sleep starts: Why your body 'hiccups' as you fall asleep

Woman wrapped up in duvet asleep
"Sleep starts usually involve one strong jerk that moves most of your body, with the arms and legs more likely to be affected. This can jolt you awake before you have the chance to fall asleep." Photo credit: Getty Images

By Sandee LaMotte of CNN

Ever drift off to sleep and suddenly feel like you're falling, forcing you to wake with a start? Some people say they are startled alert by a loud snapping noise or a blinding light coming from inside their head, while others describe their muscles twitching involuntarily from a sudden electric shock.

"Sleep starts usually involve one strong jerk that moves most of your body, with the arms and legs more likely to be affected. This can jolt you awake before you have the chance to fall asleep," said sleep specialist Dr Raj Dasgupta, an associate professor of clinical medicine at the University of Southern California's Keck School of Medicine.

Chris Breitigan, a 29-year-old podcast producer from Huron, Ohio, says he's sometimes awakened by a rather ghostly experience.

"I'll be right on the verge of falling asleep, and it's like someone tickles me," he said. "It starts from my back and moves down through my legs. I startle and get a sort of jerk in my body."

The experience may be accompanied by a rapid heartbeat, faster breathing, sweating or a vivid dream or hallucination, according to scientists.

Sleep starts, officially called "hypnic jerks," are normal occurrences that can happen to men and women of any age and are typically nothing to worry about, Dasgupta said.

"It's estimated that nearly 70 percent of the population experience sleep starts at some point," he said. "Medically speaking, hypnic jerks are classified as a type of myoclonus, which is a category of rapid, involuntary muscle movements. A classic example of myoclonus are hiccups."

No one knows precisely why the body twitches while falling asleep, but experts believe excessive caffeine intake, and physical or emotional stress may increase their frequency.

"They also may be facilitated by fatigue or sleep deprivation," Dasgupta said. "However, most hypnic jerks occur essentially at random in healthy people."

Breitigan's sleep is typically disturbed after going out with friends on Taco Tuesday nights.

"I really don't drink much," he said. "But on Tuesdays, I go out with friends and we have some drinks with tacos. So for me it seems it's triggered by alcohol because I don't drink regularly."

When to worry

There is no treatment for sleep starts, Dasguta said, and they are generally harmless. However, it's time to visit the doctor if you experience any of the following symptoms: multiple muscle jerks during the day, an injury caused by hypnic jerks, tongue or mouth biting while you sleep, or wetting the bed.

"Hypnic jerks can sometimes be confused with seizures," Dasgupta said. "While they may seem similar, they have some key differences: Seizures are a serious occurrence that can be a result of an underlying condition.

"Hypnic jerks, on the other hand, are benign phenomena that aren't tied to any health conditions or concerns," he said. "Mainly they're just annoying, especially if they keep preventing you from falling asleep."

However, some people develop a fixation on these jolts from slumber, leading to increased anxiety about the disruptive experience, he added.

"This increased anxiety and fatigue increases the likelihood of experiencing these jerks, resulting in a vicious cycle of insomnia and sleep deprivation," Dasgupta said.

Try these fixes

For anyone bothered by such events, Dasgupta has the following suggestions:

Reduce caffeine intake: Drinking less caffeine throughout the day can help improve your overall quality of sleep, Dasgupta said, especially if you avoid caffeine in the late afternoon and at night.

Avoid or reduce alcohol near bedtime: The same applies to alcohol, he said. Alcohol may make you sleepy but when the body is finished metabolising it, you will wake, typically in the middle of the night. That will increase your fatigue, making you more vulnerable to hypnic jerks.

Try meditation and mindfulness before bed: Relaxing the body may ease that transition into sleep, making your muscles less likely to twitch, Dasgupta said.

"Also, one of the best ways to help yourself fall asleep is focusing on breathing. Most breathing exercises for sleeping usually involve slow and deep breaths," he said.

Keep to a sleep routine: Dasgupta said the best sleep requires a set bedtime - even on weekends and holidays. It also helps to avoid bright screens at bedtime.

"The bright light of a TV, computer or smartphone can affect your sleep patterns and keep you alert when you should be getting sleepy," he said. "Sleeping is something you've done your whole life, but the older you get, the harder it can get to fall asleep, so practise good sleep hygiene."