Night-to-night changes in OSA severity linked to heart attack, heart failure and stroke

By Rebecca Jenkins

High night-to-night variability in obstructive sleep apnoea (OSA) severity is linked to higher odds of nonfatal major cardiovascular and cerebrovascular events (MACCEs), an Australian study finds.

Researchers analysed data from 3159 adults (19% female, median age 49 years) who had used an under-mattress sensor to track nightly OSA variability over six months and then answered questions about their general health, doctor-diagnosed disorders and health-related behaviours.

The data, published in Sleep, showed high night-to-night OSA variability was associated with a 34% increase in the odds of having reported a MACCE on the questionnaire.

This increased risk was independent of average OSA severity, doctor-diagnosed OSA, and other sociodemographic and health-related behaviours, the Flinders University-led research team reported.

‘These novel findings further add to the growing literature that indicates that highly variable OSA severity is associated with poorer cardiovascular health, and is currently uncaptured with gold-standard single-night diagnostic practices,’ they concluded.

The findings were supported in a separate Flinders University-led study, published in npj Digital Medicine, that tracked almost 30,000 people using under-mattress sleep sensors to monitor OSA severity and snoring and a smart scale to measure pulse wave velocity (PWV).

Here, increasing OSA severity and higher snoring burden both predicted higher PWV – a marker of vascular ageing and cardiovascular risk.

Of note, participants with mild OSA but high night-to-night variability had PWV levels comparable with those with severe OSA, the researchers reported.

Professor Matthew Naughton, Adjunct Professor of Medicine at Monash University, Melbourne, and Head of the General Respiratory and Sleep Medicine Service at the Alfred Hospital, Melbourne, said the papers added to the growing evidence base linking OSA with cardiovascular disease.

But he stopped short of recommending multinight studies, saying a single sleep study was adequate, providing it was conducted by an experienced sleep physician and included a thorough history and examination with full analysis of body position and sleep stages.

It was, however, necessary to repeat the study if there were changes in the patient’s weight (>5%), medication schedule or alcohol use, or if other medical or psychological conditions developed, he said.

‘If multinight studies are indicated, the issue is by what means? These two studies used under-mattress sensors, with no oximetry or ECG. There are also smart watches, wristbands and rings, with each device having pros and cons,’ he said.

The latest findings did highlight the importance of investigating snoring, Professor Naughton said, but he acknowledged it was a common complaint together with insomnia and fatigue.

‘The four key reasons to investigate snoring are: impaired cognition, high cardiovascular risk, loud snoring that upset other and/or concern from a dentist, ENT surgeon or anaesthetist – who might have noticed delayed postoperative recovery,’ he said.

Validated questionnaires were a good place to start an assessment, Professor Naughton added, such as the Epworth Sleepiness Scale, STOP-Bang (for OSA) and the Hospital Anxiety and Depression Scale.

‘A community concern is safety to drive. Although sleep apnoea is a risk factor for collisions, other factors, such as sleep deprivation and shift work, should also be considered in the context of driving history: how many kilometres per annum they drive and when they last had a significant crash which required first responders,’ he said.

Sleep 2026: zsag084 and npj Digit Med 2026; 9: 286. https://doi.org/10.1038/s41746-026-02469-w.