Women who often wake in night ‘twice as likely to have strokes or heart attack’
Women who often wake up in the night are up to twice as likely to suffer strokes or heart attacks, a new study has claimed.
However doctors say the risk could be reduced if women lose weight, block sounds out with ear plugs or treat snoring.
The findings have been revealed following a long-term research project into “unconscious wakefulness” during the night which everyone experiences.
It is part of the body’s ability to respond to situations that could be dangerous such as pain, noise, light and temperatures.
Snoring can also cause “unconscious wakefulness” as it is a result of someone’s breathing being obstructed.
Most sleepers will have no recall of experiencing “unconscious wakefulness” but they will feel very tired the next morning.
The research, undertaken by the University of Adelaide in Australia, was published in the European Heart Journal on Tuesday.
It said the sleep disruptions are linked with health issues including higher blood pressure.
They used information gathered from three studies where 8,000 men and women wore a sleep monitor during one night’s sleep.
Each were given a percentage score of “arousal burden” made up of how often they woke in the night, for how long, and compared to how long they slept for in total.
The long-term study meant participants were followed up from an average of six years to 11 years and it found women woke up in the night less than men.
However the impact of “unconscious wakefulness” appeared to be greater with women.
The study, led by associate professor Mathias Baumert, found women were at a higher risk of death from cardiovascular disease – health conditions that affect the heart or blood vessels, such as stroke or heart attack.
Women who woke up in the night most (6.5 per cent of their night’s sleep) had between a 60 and 100 per cent (double) greater risk of dying from cardiovascular disease than females who had an uninterrupted night’s sleep.
The risk of death by cardiovascular disease was 12.8 per cent compared to 6.7 per cent while the risk from other causes rose by between 20 and 60 per cent.
In total the risk increased from 21 per cent in the general population of women to 31.5 per cent.
Men had a less significant risk, as those who woke up the most had a risk of 13.4 per cent and 33.7 per cent of dying from cardiovascular disease from any cause, respectively.
This compares to 9.6 per cent and 28 per cent in men who enjoyed a full night’s sleep.
Co-author Dominik Linz, associate professor in the cardiology department at Maastricht University Medical Center in Holland, said it was unclear why it differs according to gender but he suggested it could be a difference in how the body responds to being woken in the night.
He claimed being older, fatter and snoring more left sleepers at a disadvantage.
He said: “While age cannot be changed, BMI and sleep apnoea can be modified and may represent an interesting target to reduce arousal burdens.
“Whether this will translate into lower risks of dying from cardiovascular disease warrants further study.
“For me as a physician, a high arousal burden helps to identify patients who may be at higher risk of cardiovascular disease. We need to advise our patients to take care of their sleep and practice good sleep ‘hygiene’.
“Measures to minimise noise pollution during the night, lose weight and treat sleep apnoea could also help to reduce the arousal burden.”
However as the study was conducted with mainly white people it doesn’t take into other ethnicities.
Participants were also older, with an average age of over 65, so the results of younger people could differ.
Previous research has also linked poor sleep to and increased risks of death from cardiovascular conditions.
Prof Borja Ibáñez, clinical research director at the Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, was not involved in this research but said disrupting circadian rhythm, better known as the “body clock”, can lead to a buildup of fat in the arteries.
The professor wrote in a paper linked with the study that it could explain the higher risk of cardiovascular problems in people who have sleeping issues.
He and colleagues wrote: “Even though many knowledge gaps on the relationship between sleep and cardiovascular disease remain to be studied in the coming years, this study provides solid evidence supporting the importance of sleep quality for a better cardiovascular health.
“What remains to be determined is whether an intervention aiming at improving sleep quality is able to reduce the incidence of cardiovascular events and mortality. While awaiting these trials, we wish you sweet dreams.”