People who frequently experience sudden jolts just as they drift off to sleep report poorer sleep quality and higher anxiety levels, according to new research published this week in PLOS Mental Health.
Researchers at the Paris Lodron University Salzburg in Austria surveyed 194 adults in Austria and Germany to compare individuals who experience sleep starts at least weekly against those who rarely or never encounter them. Sleep starts, also known as hypnic jerks, happen in the transitional phase between wakefulness and sleep.
“much more than a simple muscle twitch when falling asleep” said Tanja Grünberger, an author of the study, sleep starts were much more than a simple muscle twitch or spasm strong enough to wake a person fully. Affected individuals often report sudden feelings of falling, electric shocks, tingling, flashes of light, or brief dream-like imagery accompanied by a racing heart and rapid breathing.
Participants in the study completed online questionnaires regarding sleep quality, insomnia severity, daytime sleepiness, unhelpful sleep beliefs, and symptoms of anxiety and depression. The survey separated participants into two equal groups, with 96 individuals experiencing weekly sleep starts and 98 serving as a control group.
Those who experienced weekly hypnic jerks reported worse overall sleep quality, more severe insomnia, and higher scores on anxiety and depressive symptoms than the control group. The frequency of the sleep starts correlated directly with sleep quality, dysfunctional sleep beliefs, and anxiety levels, though researchers found no direct link to depression.
Demographic factors alongside sleep frequency and cognitive beliefs accounted for roughly a quarter of the variance between the groups at 26.9%. Participants also said that psychological stress and emotional strain increased the frequency of sleep starts, whereas sleep deprivation showed less impact.
“Participants described not only jerks, but also sensations of falling, a racing heart, flashes of light or loud bangs, and strong feelings of alarm or fear – and those who reported sleep starts at least once a week also reported poorer sleep quality, more unhelpful beliefs about sleep and more anxiety symptoms,” said Tanja Grünberger, an author of the study, 1News reported.
Grünberger said that the data revealed a close connection between the nocturnal jolts and thought patterns surrounding rest. “The more strongly participants held unhelpful beliefs about sleep and the more anxious they were, the more often they reported sleep starts – and in the moment itself, many described a strong pressure to finally fall asleep,” she told 1News.
Senior author Manuel Schabus said that while sudden awakenings remain a harmless feature of falling asleep for most people, the phenomenon becomes intertwined with distress for a specific subgroup. “Whether approaches that reduce arousal and sleep-related worry also help with distressing sleep starts has not yet been tested – that is an important next step,” Schabus said.
Researchers have not established a single definitive cause, though data indicates that psychological stress, emotional strain, and heightened anxiety strongly correlate with increased frequency.
The study notes that for most individuals, suddenly jolting awake remains a harmless feature of falling asleep, though frequent occurrences tie into distress and prolonged sleep onset.
The research surveyed 194 adults across Austria and Germany, dividing participants evenly between a control group and those experiencing weekly episodes.
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