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.
Physical activity and healthy sleep
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.