For years, received wisdom had it that humans need eight hours of sleep to be fit and firing on all cylinders. Now, new research has found that it isn’t just the quantity, but also the quality of sleep that matters. This research, which will be presented at an American College of Cardiology conference today, finds that higher the quality of sleep, lower the chances of cardiovascular mortality.
For this study, titled Low-risk Sleep Patterns, Mortality, and Life Expectancy at Age 30 Years: A Prospective Study of 172,321 U.S. Adults, researchers analysed data from people with an average age of 50 (54% of the respondents were women) with a median follow-up of 4.3 years. During the assessment period (2013-2018), over 8,000 respondents died, with the single largest cause of death being cardiovascular disease, and the second being cancer.
For the study, the researchers assessed five factors to determine the quality of sleep: Ideal sleep duration of seven to eight hours a night; difficulty in falling asleep no more than two times a week; trouble staying asleep no more than two times a week; not using any sleep medication; and feeling well rested after waking up at least five days a week.
People who ticked all five factors were 30% less likely to die for any reason, 21% for cardiovascular disease, 19% for cancer, and 40% for other assorted reasons. What emerged from the data was that respondents who slept longer and better were more likely to see gains in life expectance. The researchers estimated these gains in life expectancy starting at the age of 30. “If people have all these ideal sleep behaviours, they are more likely to live longer,” Dr. Frank Qian, co-writer of the study, said. “So, if we can improve sleep overall, and identifying sleep disorders is especially important, we may be able to prevent some of this premature mortality.”
“You can sleep for 12 hours and still suffer from poor sleep,” says Dr. Ashish Kumar Prakash, respiratory and sleep medicine consultant at Medanta Hospital, Gurugram. “Quality sleep is when we achieve the N3 stage of sleep and REM (rapid eye movement). That’s when we and our brain are the most relaxed. If you are in bed for 7 hours and have deep sleep for at least 5 or 6… that is good quality sleep. But you can also spend 7 hours in bed and only have 15 minutes of deep sleep and that is not good quality sleep.”
Good quality sleep improves brain performance, mood and health, says Dr. Vikas Maurya, director and head of the department of pulmonology and sleep disorders at Fortis Hospital in Delhi. “When sleep quality deteriorates, the risk of several diseases and disorders, ranging from heart diseases and stroke to obesity and dementia, increases. Higher quality sleep helps the brain prepare to learn, remember and create while also helping the repair of our immune systems,” adds Maurya.
He also addresses the misplaced belief that older adults require less sleep compared to younger adults. “The truth is that older adults need the same amount of sleep as younger adults because sleep is very important to prevent various heart and other diseases and it also performs a restorative function for our vital organs. Therefore, a good amount of sleep and good quality sleep is important in older adults as well,” he says.
Maurya says women experience better sleep quality compared to men along with longer sleep times, shorter sleep onset and higher sleep efficiency. But women also have more sleep-related complaints as menstrual cycles, pregnancy and menopause can alter the sleep architecture. Certain sleep disorders, such as REM sleep disorder and sleep apnea, seem to be more common among men while insomnia and restless leg syndrome are more prevalent among women, points out Maurya.
The study too states that men and women are impacted differently by the quality of their sleep. Among men and women who reported having all five quality sleep measures, life expectancy was 4.7 years greater for men and 2.4 years greater for women compared with those who had none or only one of the five favourable elements.
Shrenik Avlani is a writer and editor and the co-author of The Shivfit Way, a book on functional fitness.