Shocking revelation in sleep apnoea as severity from night to night increase heart and stroke risks by a third

People whose sleep apnoea changes significantly from night to night are 30 per cent more likely to have a heart attack, stroke or heart failure, new research has found. The Australian study discovered that it is not just how severe sleep apnoea is that matters, but how much it fluctuates from night to night. Lead author Bastien Lechat, from Flinders University, said people whose sleep apnoea severity varies from night to night were about one third more likely to have had a heart attack, stroke or heart failure, even after accounting for their average sleep apnoea severity. “Many people assume sleep apnoea is stable, but the reality is very different, and some nights can be much worse than others, and this repeated up and down strain may place extra stress on the heart,” Dr Lechat said. “A single night sleep test may falsely reassure some patients, because people with mild average sleep apnoea can still be at higher risk if their breathing problems swing dramatically between nights.” Obstructive sleep apnoea (OSA) causes repeated pauses in breathing during sleep. It is characterised by loud snoring, restless sleep and daytime fatigue. OSA severely disturbs sleep and is a stress on the body. People with untreated moderate to severe OSA have increased risk of high blood pressure, heart attack, diabetes, depression and stroke, according to the Sleep Health Foundation. Research from the WA Raine study published in 2022 found that 70 per cent of 1005 middle-aged people had some form of sleep apnoea — and in 34 per cent it was deemed clinically significant. This new study analysed sleep data from more than 3000 people who tracked their breathing at home using an under-mattress sensor. Their sleep patterns were measured over several months and compared with reported heart and stroke conditions. Danny Eckert, director of FHMRI Sleep Health at Flinders University, said the body may struggle to adapt to repeated changes in oxygen levels and sleep disruption. “These night‑to‑night swings can quietly stress the heart and blood vessels over time without being picked up by standard testing,” he said. A second Flinders University-led study, published in February, found that severe sleep apnoea, high night to night variability and habitual snoring were all linked to faster ageing of blood vessels, which is an early warning sign of cardiovascular disease. Most people are tested for sleep apnoea have their breathing measured for one night only. Lucia Pinilla, who led the second study, said both studies showed why repeated sleep monitoring was so important. “These findings show that one-night tests can miss people at real risk,” says Dr Pinilla. “Sleep should be seen as a moving picture rather than a single photograph, and understanding nightly patterns can help doctors better identify who needs early intervention,” she says.