woman napping in the sun after exercisingShare on Pinterest
New research shows how physical activity and good sleep work together to promote health. Justin Paget/Getty Images
  • Study shows physical activity and quality sleep have synergistic effects on health.
  • Higher levels of physical activity may significantly counteract the negative health impact of poor sleep.

While the negative health effects of physical inactivity and poor sleep have been independently researched and documented numerous times, few studies have focused on the synergistic impact of these factors on mortality.

A study published in the British Journal of Sports Medicine investigates the joint association of physical activity and sleep with all-cause and cause-specific mortality risks.

The long-term study followed over 380,000 middle-aged men and women who are part of the UK Biobank.

The participants completed questionnaires, interviews, and physical measurements to determine their baseline health condition along with their physical activity levels and sleep behaviors.

Individuals were excluded from participating in the study if their baseline assessments indicated a history of cardiovascular disease, cancer, sleep apnea, or class 3 obesity.

The researchers assessed and summarized physical activity data using metabolic equivalent task minutes. These minutes are roughly equivalent to the number of calories expended per minute of physical activity.

Individual physical activity was categorized based on the World Health Organization (WHO) guidelines. Categories included:

  • high (1200 or more minutes per week)
  • medium (600 to less than 1200 minutes per week)
  • low (0 to less than 600 minutes per week)

The researchers defined another category to include no moderate-to-vigorous activity per week so that they could also assess the effects of insufficient physical activity.

The negative health effects of poor sleep encompass more than just sleep quality or duration, and therefore the researchers applied a novel healthy sleep score.

They used five sleep characteristics — chronotype (night owl vs. morning lark tendencies), sleep duration, the presence of insomnia, daytime sleepiness, and snoring — to score participants on a scale from 0 to 5. Sleep score categories included: healthy (4 or higher), intermediate (2–3), and poor (0–1).

Using both these scoring methods along with other information supplied by the participants, the researchers derived a dozen physical activity/sleep combinations.

The participants’ health was then tracked until May 2020 or their death, depending on which came first, to assess their risk of dying from any cause, and specifically from cardiovascular disease, coronary heart disease, stroke, and all types of cancer. These are the common issues independently associated with poor sleep and minimal physical activity.

Around 15,500 participants died during the monitoring period.

Approximately 26% of the deaths were from any type of cardiovascular disease; 58% were from all types of cancer; 12% resulted from coronary heart disease; 2% followed a brain bleed stroke; and 3% were from a blood clot stroke.

Those who died during the first 2 years of the study were excluded from the data, as was anyone who died from COVID-19.

The results of the study indicate that the lower a participant’s sleep score, the higher their risk of death from any cause and from all types of cardiovascular disease and blood clot-induced stroke.

Also, those who had poor sleep and no moderate-to-vigorous physical activity had the highest risk of death from any cause, from cardiovascular disease, and from any type of cancer when compared with those having a high-physical-activity-plus-healthy-sleep combination.

People who were younger, female, slimmer, and financially better off, consumed more fruits and vegetables, spent less of their days sitting, had no mental health issues, never smoked, drank less alcohol, and were more physically active tended to have healthier sleep scores.

The researchers acknowledge limitations within the study, including the fact that this was an observational study, which means that it does not establish causality.

Also, the study relied on self-reported data and excluded potentially influential factors, such as occupation, household size, and possible changes in sleep behavior and physical activity over time.

According to the researchers, “Poor sleep was associated with a higher risk [of] all-cause and cause-specific mortality, and these risks were markedly exacerbated among participants with insufficient [physical activity].”

The study results also indicate that levels of physical activity at or above the lower threshold recommended by the WHO appeared to eliminate most of the detrimental associations of poor sleep and mortality.

The researchers conclude that emerging evidence supports a synergistic effect of sleep and physical activity on health outcomes. They stress the need for future studies to include device-based sleep and physical assessments that will concurrently target both behaviors.