People who frequently startle awake while falling asleep—a phenomenon researchers call "sleep starts" or hypnic jerks—report poorer sleep quality, greater insomnia severity, and higher anxiety than those who do not, according to a new study published this week in the open-access journal PLOS Mental Health by Tanja Grünberger and Manuel Schabus of Paris Lodron University Salzburg, Austria, and colleagues.
Sleep starts are sudden jolts that occur in the moments between wakefulness and sleep, most often felt as an abrupt muscle jerk or twitch, sometimes strong enough to jolt a person fully awake. The experience can also involve a sudden sensation of falling or loss of balance, electric-shock-like feelings, tingling or numbness, flashes of light, or brief, dream-like imagery. These experiences are frequently accompanied by a rush of emotion—alarm, confusion, fear, or panic—and physical signs of a startle response, such as a racing heart or rapid breathing. Afterward, most people fall back asleep quickly.
In the new study, researchers conducted an online survey of 194 adults in Austria and Germany who answered questions about their sleep quality, insomnia severity, daytime sleepiness, dysfunctional sleep-related beliefs, and symptoms of anxiety and depression. 96 of the participants experienced abrupt awakenings and at least one other symptom weekly, while the other 98 were used as a control group.
Compared with the control group, the sleep-starts group reported poorer sleep quality, greater insomnia severity, more dysfunctional sleep-related beliefs, and higher anxiety and depressive symptoms than those in the control group (all statistically significant). How often people experienced sleep starts was also linked to sleep quality, sleep beliefs, and anxiety, but not depression. Together, these factors, along with age and gender, were associated with about a quarter of the differences between people in sleep start frequency (26.9%). Participants also reported more frequent sleep starts during periods of psychological stress and emotional strain, whereas sleep deprivation was less influential on the frequency of sleep starts.
"These findings support the view that sleep starts should be considered within broader frameworks of sleep-related hyperarousal and cognitive-emotional activation," the authors write. "Although causality cannot be inferred from these cross-sectional self-report data, the results highlight potentially relevant links between sleep starts and sleep-related cognitive-emotional processes."
"These findings support the view that sleep starts should be considered within broader frameworks of sleep-related hyperarousal and cognitive-emotional activation," the authors write. "Although causality cannot be inferred from these cross-sectional self-report data, the results highlight potentially relevant links between sleep starts and sleep-related cognitive-emotional processes." First author Tanja Grünberger says: "Because there is no established questionnaire for sleep starts, we developed our own items based on the clinical literature. This allowed us to capture a broad range of experiences – but it also means that our findings now need to be confirmed with validated instruments and objective sleep recordings."
Dr. Grünberger adds: "Sleep starts are much more than a simple muscle twitch when falling asleep. 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."
She continues: "What we found most interesting was how closely sleep starts are linked to how people think and feel about sleep. 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. Our data cannot show what causes what, but this pattern resembles what we know from insomnia."
Senior author Manuel Schabus explains prospective next steps for their research: "For most people, sleep starts are a harmless feature of falling asleep. For a subgroup, however, they go along with distress and a longer time to fall asleep. 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."
In your coverage please use this URL to provide access to the freely available article in PLOS Global Public Health: https://plos.io/4zDFlq7
Citation: Grünberger T, Höhn C, Schabus M, Laireiter A-R (2026) Sleep starts: Phenomenology and associations with sleep, psychological, and demographic characteristics. PLOS Ment Health 3(11): e0000737. https://doi.org/10.1371/journal.pmen.0000737
Author Countries: Austria
Funding: The authors received no specific funding for this work.
