“Women and men may have different compensatory mechanisms for coping with the detrimental effects of [cortical] arousal. Women may have a higher arousal threshold and so this may result in a higher trigger burden in women compared to men.”

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Sanjay Sharma, professor of cardiology at St George’s University of London in Britain, says it could be because of women responding to stress differently and having “relatively higher circulating stress hormones”.

Unconscious wakefulness occurs spontaneously and is part of the body’s ability to respond to potentially dangerous situations, such as an external noise or our breathing becoming obstructed. Pain, limb movements, trauma, temperature and light are also potential triggers.

“Depending on the strength of the arousal, a person might become consciously aware of the environment, but often that is not the case. Typically, people will feel exhausted and tired in the morning because of their sleep fragmentation but will not be aware of the individual arousals,” says Linz.

Previous research has shown that sleep duration, whether it’s too short or too long, is associated with increased risks of death from cardiovascular causes. Until now, it was not known whether there was also a link between the number of cortical arousals and their duration, and the risk of death.

The research showed that although sleep disturbance was caused by insomnia in up to 15 per cent of cases, there were several other factors too, including stress, profession, environmental noise and excessive use of stimulants, tobacco or alcohol.

Linz says the findings reiterated that reducing noise pollution and losing weight could help to reduce the arousal burden in patients who were potentially at higher risk of cardiovascular disease.

“We need to advise our patients to take care of their sleep and practise good sleep hygiene,” he adds.

Sharma suggested people should make “concerted efforts” to sleep seven to eight hours each night.

Professor Borja Ibanez, clinical research director at the Spanish National Cardiovascular Research Centre in Madrid, says: “Even though many knowledge gaps on the relationship between sleep and cardiovascular disease remain, this study provides solid evidence supporting the importance of sleep quality for a better cardiovascular health.”

European Society of Cardiology spokesman Professor Paul Dendale agrees the “strong” research shows a clear relationship between the number of times a person wakes up and the risk of cardiovascular problems in the future. But he cautions there were no certainties that sleep disorders were the direct cause of the cardiovascular disease.

The findings come as research from China’s Shandong University reveals female Chinese patients are more likely to refuse specialist heart attack treatment. The procedure, known as percutaneous coronary intervention, combines coronary angioplasty (in which a balloon is inserted into a blocked artery of the heart to clear it) with stenting (inserting a tiny tube into a blocked artery to keep the line open).

The study published in the Chinese Medical Journal found many patients – particularly women – with a severe type of heart attack chose not to undergo the procedure. Female patients less likely to have the treatment were older, less likely to be married, had lower body mass index values and were less likely to receive treatment at tertiary hospitals.