Many people have experienced irregular sleep from time to time, but new research has pointed out why disruptive sleep can raise the risk of early death — especially in women.
The findings from a study, which was published in the European Heart Journal Tuesday, shows a definite connection between the frequency and duration of unconscious wakefulness while sleeping at night and a heightened risk of dying from cardiovascular diseases. This association was also found to be tied to any cause of death.
“It is unclear why there is a difference between men and women in the associations, but there are some potential explanations,” Dominik Linz, associate professor in the cardiology department at Maastricht University Medical Center in the Netherlands, said of the risk women in particular face. “The triggers causing an arousal or the body’s response to arousal may differ in women compared to men. This may explain the relatively higher risk of cardiovascular death in women. Women and men may have different compensatory mechanisms for coping with the detrimental effects of arousal. Women may have a higher arousal threshold and so this may result in a higher trigger burden in women compared to men.”
The study evaluated 8,001 participants who were part of three separate studies. On average, the men and women involved were ages 77, 83 or 64 depending on the study. Participants were tracked for several years, ranging from six years on average to 11 years.
Results showed that women who most frequently experienced unconscious wakefulness for longer lengths of time had almost two times the risk of dying from cardiovascular disease during the average follow-up period compared to the risk among the general female population. Links between these two experiences weren’t as clear in men. Additionally, men’s risk of cardiovascular death grew by just over a quarter compared to the general male population.
A normal part of sleep, unconscious wakefulness occurs spontaneously. In part, it is the body’s response to potentially dangerous conditions, including noise or hindered breathing. Other possible triggers are light, temperature, limb movements, pain and trauma.
“A common trigger for nocturnal arousals is obstructive sleep apnoea when breathing stops and the arousal system ensures the activation of our body to change our sleep position and to reopen the upper airway,” Linz said. “Another cause of arousals can be ‘noise pollution’ during the night by, for example, night-time aircraft noise. 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.”
Study limitations included that the participants were older and mostly white. As such, the findings cannot be extended to include younger men and women or other races. Additionally, it demonstrates a link between greater sleep arousal burden and increased risk of death rather than a direct cause.
“Even though many knowledge gaps on the relationship between sleep and CVD [cardiovascular disease] remain to be studied in the coming years, this study provides solid evidence supporting the importance of sleep quality for a better CV health,” researchers said. “Further evidence combining comprehensive sleep evaluation with biological sampling and long-term follow-ups will be desirable . . . What remains to be determined is whether an intervention aiming at improving sleep quality is able to reduce the incidence of CV events and mortality. While awaiting these trials, we wish you sweet dreams.”
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