Poor sleep habits increase risk of hypertension, stroke

New research from Flinders University shows the chance of higher blood pressure increases exponentially, particularly for overweight middle-aged men, with every hour of sleep they lose or change to their regular night-time routine.

The study, published in the journal Hypertension, involved a global sample covering the equivalent of more than 2 million nights of home sleep data measured from 12,287 adults — 88% of them men and, on average, overweight — in their own homes using portable under-mattress sensor monitoring technology and remote blood pressure assessment. On average, each participant had 30 separate blood pressure recordings over the nine-month study timeframe.

The research team found a strong correlation between elevated hypertension and irregular sleep duration and timing, emphasising the need for more awareness about the links between circadian control systems and health.

“Not only should we monitor the amount of sleep, but we should also keep our resting schedule as regular as possible,” said sleep psychology researcher Dr Hannah Scott, a co-lead author on the study.

Regularly varying nightly bedtimes by more than about 30 minutes was associated with a 32% increase in hypertension risk. Higher nightly variability in other timing measures — such as mid-sleep time and wake-up time — were associated with greater hypertension risk.

Given a complex interplay between sleep history, sleep need and circadian influences, irregular sleep can lead to further disruption and even more variation in sleep patterns, researchers warn. Furthermore, inadequate sleep (less than six hours) and even too much sleep (long sleep of nine or more hours) were also associated with increased blood pressure, similar to other studies.

“These findings illustrate how irregularity in both duration and timing of sleep onset and waking up is a clear risk marker for poor cardiovascular health, along with the total number of hours we sleep,” said study co-author Dr Bastien Lechat.

“Further investigations may find other cardio and health issues are connected to day-to-day fluctuations in sleep duration and timing.”

Just a few days later, a separate study published in the journal Neurology revealed that people who have sleep problems may be more likely to have a stroke. Sleep problems included getting too much or too little sleep, taking long naps, having poor-quality sleep, snoring, snorting and sleep apnoea. In addition, those who had five or more of these symptoms had an even greater risk of stroke.

The international study involved 4496 people (average age 62 years), including 2243 people who had had a stroke and 2253 who had not. Participants were asked about their sleep behaviours including how many hours of sleep they got, sleep quality, napping, snoring, snorting and breathing problems during sleep.

People who slept for too many or too few hours were more likely to have a stroke than people who slept an average number of hours. A total of 162 of those who had a stroke got less than five hours of sleep, compared to 43 of those who did not have a stroke. And 151 of those who had a stroke got more than nine hours of sleep a night, compared to 84 of those who did not have a stroke.

Researchers found that people who got less than five hours of sleep were three times more likely to have a stroke than those who got seven hours of sleep on average. People who got more than nine hours of sleep were more than two times as likely to have a stroke than those who got seven hours a night. People who took naps longer than one hour were 88% more likely to have a stroke than those who did not.

People who snored were 91% more likely to have stroke than those who did not and people who snorted were nearly three times more likely to have a stroke than those who did not. People with sleep apnoea were nearly three times more likely to have a stroke than those who did not. After adjusting for other factors that could affect the risk of stroke, such as smoking, physical activity, depression and alcohol consumption, the results remained similar.

“With these results, doctors could have earlier conversations with people who are having sleep problems,” said study author Christine McCarthy, from the University of Galway. “Interventions to improve sleep may also reduce the risk of stroke and should be the subject of future research.”

Image caption: Dr Hannah Scott, Dr Bastien Lechat and Professor Danny Eckert at the FHMRI Sleep Health research centre at Flinders University.