Hungarian researchers have discovered the depressing health risks of getting too much sleep
According to a recent study published by a research team at a Hungarian university, surprisingly, not only insufficient but also excessive sleep may pose health risks.
How much do you sleep?
Sleeping too little or too much increases the risk of death and stroke, according to a comprehensive analysis published in the journal GeroScience by Semmelweis University. The study found that people who consistently sleep less than seven or more than nine hours a day face a higher risk of mortality.
According to the study, those who sleep fewer than seven hours per night have a 14% higher risk of death. The danger is even greater for those who regularly get nine or more hours of sleep, with the risk rising by 34% compared to those who sleep seven to eight hours a night. The research analysed data from over 2.1 million adults across 79 international publications examining both short and long sleep duration.
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Too much or too little sleep poses health risks, new study shows
The findings also revealed significant gender differences:
Among men, sleeping less than seven hours increased mortality risk by 16%, while more than eight hours raised it by 36%. For women, short sleep duration increased the risk by 14%, while long sleep raised it by 44%.
The study suggests that hormonal, behavioural, or cardiovascular factors could explain these differences, though the exact causes remain unclear. Chronic insomnia was identified as the most common sleep disorder. Previous research has shown that one-third of the global population experiences insomnia at least once in their lives, and about 10% suffer from chronic insomnia.
Researchers warn that sleep deprivation is becoming a major global public health issue. Millions worldwide are sleeping too little due to increased workloads, constant use of digital devices, and persistent stress. Those working night shifts or with irregular schedules are particularly at risk. Long-term sleep deprivation is linked not only to increased mortality but also to a range of health issues, including obesity, diabetes, cardiovascular diseases, and weakened immune function.
A societal-level problem
We may be facing a sleep epidemic, according to the publication quoting György Purebl, Director of the Institute of Behavioural Sciences at Semmelweis University and co-author of the study. “Although health awareness has increased, our behaviour has barely changed over the past decade. The time spent in front of screens, the resulting constant exposure to blue light, being perpetually available, and the disruption of our biological rhythms all negatively impact our health,” he added.
In a separate study, researchers examined the link between sleep duration and the frequency of stroke and stroke-related deaths. People who slept 5–6 hours per night had a 29% higher likelihood of experiencing a stroke and a 12% greater risk of stroke-related mortality. For those who slept more than 8–9 hours, stroke incidence increased by 46%, and the risk of death rose by 45%.
“Stroke remains one of the leading causes of death worldwide and often results in permanent disability,” said Balázs Győrffy, Head of the Department of Bioinformatics at Semmelweis University and author of both studies. “Lifestyle factors like sleep are modifiable, which makes identifying them a key public health opportunity. Sleep duration should be considered in stroke prevention strategies to reduce the burden on healthcare systems and improve population health.”
According to the World Health Organisation, 15 million people suffer strokes each year.
Of those, five million die and another five million are left with permanent disabilities, including loss of speech or vision, paralysis, or cognitive impairments. Most cases could be prevented by managing blood pressure and avoiding smoking.
How to prevent the problem?
Experts recommend establishing a consistent sleep routine, limiting screen time and bright lights before bed, and creating a dark, cool, and quiet sleeping environment. Avoiding alcohol, consuming caffeine in moderation, and engaging in regular physical activity can also promote restful sleep.
The meta-analyses were conducted as part of the long-term Semmelweis Study, which follows university employees to examine how lifestyle factors—such as sleep—affect health. The goal is not only to support institutional health initiatives but also to help shape broader public health recommendations.
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