Several studies prove that sleep disorders have an important influence on our psychophysical health. Usually, researchers focus their investigations mainly on the quality and length of time we spend resting, but a team of British scientists have also discovered what appears to be a correlation between when we fall asleep and the risk of cardiovascular disease such as heart attack. stroke and ischemic attack.
Objective measurements. According to this study published in the European Heart Journal, the negative effect on heart health would not depend on how many hours you sleep, but on the time chosen to turn off the light: the ideal time would be between 22 and 23 (now solar, so with spring-summer daylight saving time it would be between 11pm and midnight).
The researchers arrived at this conclusion by monitoring, between 2006 and 2010, 88,026 people aged between 43 and 79 years: 58% female and 41.6% male. Important: all subjects had a wrist accelerometer to record, for seven days, the time they went to sleep and the time they woke up. In other words, the measurements were objective and not based on sleep diaries or questionnaires as is often the case.
An hour more or less makes the difference. After about six years of gathering the information, the researchers found 3,172 people developed cardiovascular disease. In detail, compared to those who went to bed between 10pm and 11pm, those who used to go to bed after midnight were 25% more likely to develop cardiac risks, and also for those who went to bed before hours 22 the result was similar – 24% – and mostly female because, after menopause, women have been shown to have difficulty sleeping. For those who fell asleep between 11pm and midnight the risk remained, but halved (12%).
The hypothesis of the researchers, after considering all the other most common cardiovascular risk factors (smoking, alcohol, blood pressure, and so on) is that sleep synchronization should correspond to the biological clock: going to bed too early or too late could indeed alter the body’s natural 24-hour rhythm, affecting biological mechanisms that increase cardiovascular risk. So, once again, a study seems to confirm that, even if our lifestyle makes us extend the day until late, synchronizing the biorhythm with the natural alternation of light and dark is essential to keep the body healthy.
We regulate the biological time. To preserve heart health – in addition to the known rules such as not smoking, eating proper nutrition and practicing sports regularly – the researchers therefore recommend resetting our biological clock and indulging in sleep no earlier than 10 pm and not after 11 pm. ? A few rules also for us adults (and not only always for children) could help us: let’s start avoiding all those habits – no cell phones and tablets before going to bed, avoiding physical activity in the evening, having little exposure to light – which prevent us from falling asleep sooner than we would like. It certainly won’t hurt us.