Quebecers are generally sleep deprived, repeat the experts, like citizens of many other countries. A healthy adult should sleep, it is said, at least eight hours a day to recover and be in good physical and mental health. But where does this rule come from, wondered the Rumor Detector.
It is certain that lack of sleep—and in some cases, excess—is associated with several health problems, including cardiovascular illnessesthe Type 2 diabetesl’obesity both among adults that childrenl’hypertensionand the general mortality. It now remains to define what a short night is.
Because studies indicate that there is no no ideal amount of sleep applicable to all. On the contrary, it should be individualized according to different factors.
Why 8 hours?
In the United States, the National Sleep Foundation established sleep durations specific to each age group. For healthy adults, the ideal duration would be seven to nine hours per night while people over 65 would need seven to eight hours. And adults who take a long time to fall asleep – more than 10 to 20 minutes – should adjust their bedtime so that they actually get eight hours of sleep.
Also in the United States, Centers for Disease Control recommend nights of seven hours or more for 18 to 60 year olds; seven to nine hours for those aged 61 to 64 and seven to eight hours for those aged 65 and over. As for the World Health Organization and theAmerican Academy of Sleep Medicinethey recommend that adults get at least seven to eight hours of sleep per night.
These guidelines therefore present a recommended time range for people who are in good health and do not suffer from sleep disorders. Sleeping an hour more or less than average may be acceptable depending on general health, daily activities, and typical sleep patterns.
In Canada, statistics compiled in 2017 indicated that Canadians aged 18 to 64 slept an average of 7.14 hours per night and that 65% of them got enough sleep (seven to nine hours). While in the elderly it was 7.24 hours per night and 54% of them slept enough (seven to eight hours).
Adverse effects of lack of sleep
People who have insomnia or sleep too much may have symptoms that tell you of serious health problems. Or, if their too short nights are the result of a deliberate choice, these people can, over a prolonged period, compromise their health and well-being, indique la National Sleep Foundation.
Several studies have shown the deleterious effects of a lack of sleep. For example, a search published last year in Nature Communications concludes that a sleep of six hours or less per night, between the ages of 50 and 70, would be associated with a higher risk of dementia by 20 to 40% compared to those who have nights of seven hours. Another study published in 2017 in Neurology shows that each 1% reduction in REM sleep time is associated with a 9% increased risk of dementia, a disorder of memory and cognitive functions. This work suggests a link between sleep duration and the risk of dementia, without however establishing a causal relationship. Thus, it is unclear whether sleep disturbances occur due to dementia or whether poor sleep habits are likely to contribute to the development of the disease.
A analyse prospective published regarding fifteen years ago indicated that sleeping five hours or less per night increased the risk of hypertension by 60% in middle-aged adults. A meta-analysis published in 2011 concluded that people who slept little were at greater risk of coronary heart disease and stroke than those who slept seven to eight hours a night. For many other studies have confirmed that insufficient sleep is detrimental to cardiovascular health.
Question of time and regularity
It’s not just the lack of sleep, it’s the lack of regularity. Waking up or falling asleep at too variable times would also increase the risk of cardiovascular problems, according to a study published in 2020 in the Journal of the American College of Cardiology. People whose sleep duration difference was two hours or more from one night to the next had a twice as high risk of such health problems.
Bedtime would also have an influence. A study published last November and conducted among 88,000 Britons aged 43 to 79, shows that people who fell asleep between 10 p.m. and 11 p.m. were those with the lowest risk of developing cardiovascular disease. When bedtime was following 11 p.m., the risk increased by 12% and following midnight, by 25%. Surprisingly, however, it’s also true the other way around: the study found that participants who fell asleep before 10 p.m. had a 24% higher risk of developing heart disease.
Finally, the duration and regularity of sleep are not enough, the quality also has its importance. People whose sleep is frequently interrupted or cut short may not have benefited enough from the different phases of sleep that mark a normal night. Poor sleep can lead to irritability and anxiety, and increase the risk of high blood pressure, heart disease, obesity, and type 2 diabetes.
Verdict
A healthy adult should sleep between seven and nine hours a night, an average of eight hours to maintain good health and reduce the risk of cardiovascular disease, among other things. In addition to the duration, the regularity and quality of sleep are also to be taken into consideration.
