Experts recommend that most adults get 7-9 hours of sleep a night.
Plenty of research points to sleep and physical activity as crucial factors affecting life expectancy. Regular exercise can lengthen life, while too little or too much sleep may cut it short.
But evidence is growing that exercise may counteract the negative effects of poor sleep. A 2022 study found that being physically active for at least 25 minutes a day can erase the risk of early death associated with too much sleep or trouble falling asleep. And a 2021 study found that lower levels of physical activity may exacerbate the impact of poor sleep on early death, heart disease, and cancer.
The latest such study, published in the European Journal of Preventive Cardiology, suggests that higher volumes of exercise can virtually eliminate the risk of early death associated with sleeping too little or too long.
This study is unique, the researchers say, because it used accelerometers (motion-tracking sensors) to quantify sleep and physical activity. Other studies asked participants to report their own data, opening the door to false reports and mistakes.
Some 92,000 participants in the United Kingdom (mean age, 62 years; 56% women) wore the activity trackers for a week to measure how much they moved and slept. In the following 7 years, 3,080 participants died, mostly from cardiovascular disease or cancer.
As one might expect, the participants who were least likely to die also exercised the most and slept the “normal” amount (6-8 hours a night, as defined by the study).
Compared with that group, those who exercised the least and slept less than 6 hours were 2.5 times more likely to die during those 7 years (P < .001). Less active persons who got the recommended sleep were 79% more likely to die (P < .001). The risk was slightly higher than that for those who logged more than 8 hours a night.
But those risks disappeared for short- or long-sleeping participants who logged at least 150 minutes a week of moderate to vigorous activity.
“Exercise fights inflammatory and metabolic dysregulations and abnormal sympathetic nervous system activity,” said study author Jihui Zhang, PhD, of the Affiliated Brain Hospital of Guangzhou (China). Those problems are associated with cardiovascular diseases and other potentially fatal conditions.
More objective data – with tech
A study’s findings are only as good as the data it relies on. That’s why obtaining objective data not influenced by individual perception is key.
“Self-report questionnaires are prone to misperception, or recall or response bias,” Dr. Zhang explains.
Take sleep, for example. Research reveals that several factors can affect how we judge our sleep. When people have to sleep at irregular times, they often underestimate how many hours they sleep but overestimate how long they nap, found a study in the Journal of Clinical Sleep Medicine.
Another study showed that when people are under a lot of stress, they’ll report more sleep problems than they actually have, as revealed by an Actiheart monitor.
With exercise, participants often report doing more exercise, and doing it at a higher intensity, than objective measurements show they did. At the same time, self-reports typically don’t account for much of the unplanned, low-effort movement people do throughout the day.