How much sleep is good for heart health?
Cardiovascular disease (CVD) is the world’s number 1 killer, being responsible for some 31% of global deaths, according to the World Health Organisation (WHO). Tobacco, unhealthy diet, physical inactivity and the harmful use of alcohol are the biggest triggers for CVDs, leading to raised blood pressure, elevated blood glucose and weight problems and obesity, all detrimental to good heart health. But a new study now suggests a critical additional risk is how long we sleep, as well as the quality of our sleep. So, while pharmaceuticals, physical activity and diet are established strategies to reduce CVD risk, not only does this study suggest sleep is an important weapon, but it emphasises that sleep may well be the key foundation of a healthy lifestyle upon which diet and exercise rest.
The study, which is different from previous types of studies, suggests people with less than six hours sleep a night (as well as those sleeping more than eight hours a night) may be at increased risk of CVDs disease compared with those who sleep between seven and eight hours. Further, poor quality sleep increases the risk of atherosclerosis – plaque build-up in the arteries.
A study unlike others
Unlike typical previous studies on sleep and heart health, this one was both larger and focused on a healthy population. And while other research mostly relied on questionnaires after-the-fact – depending upon individual evaluation – this study employed actigraphs to obtain objective measures of sleep. It also used 3D ultrasound to measure atherosclerosis throughout the body, as well as cardiac CT scans to look for heart disease. So, while previous studies have shown that lack of sleep raises the risk of CVD by increasing heart disease risk factors such as glucose levels, blood pressure, inflammation and obesity, this was reported by the researchers as the “first study to show that objectively measured sleep is independently associated with atherosclerosis throughout the body, not just in the heart.”
Participants were Spanish bank employees without known heart disease and two-thirds were men. After allowing for other risk factors, those sleeping less than six hours were 27% more likely to have atherosclerosis throughout the body compared with those who slept seven to eight hours. Likewise, participants with poor sleep quality were 34% more likely to have atherosclerosis. Sleep quality was determined by how often a person woke-up, as well as the frequency of movements during the sleep, which reflect the sleep phases.
As a result, the researchers also concluded that good quality shorter sleep duration can reduce the detrimental effects of the shorter length. Interestingly, the findings also suggested sleeping more than eight hours is a potential problem, with the researchers finding women who slept more than eight hours a night also had an increased risk of atherosclerosis.
Top tips for a good night’s sleep
- Create a ‘sleep time’ and space
- Keep the bedroom on the cool side, at least a few degrees lower than ‘waking space’
- Banish televisions, phones, Ipads
- Avoid caffeine in the evenings and go light on alcohol
- Banish night-time snacks
Regular exercise can help, but not within three hours of bedtime. Interestingly, the causation seems to be sleep helps us to exercise, which helps us sleep, rather than the other way around; just consider how a poor night’s sleep destroys exercise performance.
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