To nap or not to nap: more questions than answers

• Published in: Heart (British Cardiac Society) Vol. 105; no. 23; pp. 1768 - 1769
• Main Authors: Leng, Yue, Yaffe, Kristine
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd and British Cardiovascular Society 01.12.2019; BMJ Publishing Group LTD
• Subjects: Cardiac risk factors and prevention; Cardiovascular disease; Coronary artery disease; Editorial; Epidemiology; Health risk assessment; Mortality; Sleep deprivation; Stroke; United States > US; San Francisco California; Stroke; Coronary artery disease; Epidemiology; Cardiac risk factors and prevention
• ISSN: 1355-6037; 1468-201X; 1468-201X
• DOI: 10.1136/heartjnl-2019-315442

A pioneering Greek case–control study from the late 1980s2 compared 97 men with an acute episode of coronary heart disease (CHD) and 90 control subjects, and showed a 30% reduction in the incidence of CHD associated with a 30 min afternoon nap. Over the past decade, growing epidemiological evidence has pointed to napping as a risk factor for cardiovascular disease (CVD), and a recent meta-analysis3 summarised 11 prospective studies and concluded that there was a J-shaped dose–response relationship, in which the risk of CVD decreased with increasing nap duration until it reached 30 min/day, but started to increase with longer naps after the 30 min/day threshold. What is the best way to measure naps? [...]we get to the answers to some of these questions, the implications of napping cannot be fully addressed. Notably, previous findings on the association between napping and increased CVD risk were mostly found among older adults,3 and it is often hypothesised that napping in the elderly could be indicative of underlying health problems. [...]the benefits of occasional napping might become less evident in this population who are already at high risk for CVD. While the authors were unable to compare the association between napping and CVD among those with <6 hours vs ≥6 hours of night-time sleep due to insufficient number of people in the former group, the association stayed robust after further adjustment for PSG-measured obstructive sleep apnoea or excessive daytime sleepiness. [...]it is unlikely that infrequent napping helps to reduce CVD risk only through compensating for poor night-time sleep.