Daytime napping is associated with increased risk for major CV events and deaths in individuals with more than 8 hours of nighttime sleep, according to findings published in the European Heart Journal.
In addition, the researchers found that sleeping 6 to 8 hours per night confers the lowest risk for all-cause mortality and CV events.
Sleep and CVD
Researchers analyzed the association of estimated total daily sleep duration and daytime nap duration with deaths and major CV events.
“Sleep is essential to human health, and people spend about a third of their hours sleeping. It is increasingly regarded as an important lifestyle behavior that can affect CVD and death,” Chuangshi Wang, a PhD student at McMaster University, Canada, and Peking Union Medical College, Beijing, and colleagues wrote. “Sleep deprivation could increase the risk of cardiovascular outcomes by reduced energy expenditure, up-regulation of appetite and altered glucose metabolism.”
Researchers used data from the PURE study to analyze 116,632 participants (median age, 50 years) to determine the primary endpoint, time to all-cause mortality plus major CV events, including fatal CV events, nonfatal MI, stroke and HF.
The researchers also stratified patients by age ( 50 years vs. < 50 years) to adjust for the need for increased sleep with increased age.
According to the findings, 4,381 participants died and 4,365 had a major CV event during a median follow-up of 7.8 years. Patients sleeping an estimated 6 to 8 hours had the lowest incidence of all outcomes vs. participants who slept shorter (HR = 1.09; 95% CI, 0.99-1.2) or longer durations (HR for 8 to 9 hours = 1.05; 95% CI, 0.99-1.12; HR for 9 to 10 hours = 1.17; 95% CI, 1.09-1.25; HR for 10 or more hours = 1.41; 95% CI, 1.3-1.53; P for trend < .0001).
The researchers identified that daytime napping increased the risk for individuals sleeping more than 6 hours per night but not for those sleeping less than that (P for interaction = .0039).
“Our findings of the possible protective effects of daytime naps among those with short estimated nighttime sleep is in keeping with results from a prior study,” Wang and colleagues wrote.
Possible risk marker
In a related editorial, Dominik Linz, MD, PhD, of the Centre for Heart Rhythm Disorders at the University of Adelaide and Royal Adelaide Hospital’s South Australian Health and Medical Research, and colleagues wrote: “Daytime napping could represent a risk marker of subclinical non-diagnosed CV disease or may even expose to higher CV risk, particularly in those with adequate sleep duration during the night. In those with short nocturnal sleep, daytime napping may be a compensatory mechanism and might be beneficial. We need to be aware, and communicate to our patients, that sleeping a lot and having daytime naps may not always be that harmless.” – by Earl Holland
Disclosures: The study and editorial authors report no relevant financial disclosures.