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expert reaction to study on sleep duration, cardiovascular events and mortality

Research published in European Heart Journal demonstrates that estimated total sleep duration of 6–8h per day is associated with the lowest risk of deaths and major cardiovascular events.


Prof Francesco Cappuccio, Chair of Cardiovascular Medicine & Epidemiology, University of Warwick, said:

“This study is confirmatory of many previous reports published in the last 10 years highlighting the importance of sleep duration as a potential contributing factor to ill-health, cardio-vascular morbidity and mortality, and all-cause mortality. The results are, therefore, not new.

“They confirm that sleeping 6-8 hours per night is associated with the lowest risk and should be considered the norm. They also confirm the presence of a U-shaped curve of risk with increased mortality for short and long sleepers, as well as for those who nap. It is valuable in that it confirms these effects are detected in diverse socio-economic and cultural settings across the world.

“However, the analysis misses the important relationship with short sleep duration, more likely to be causally related to ill-health, whilst overestimating the association with longer sleep, unlikely to cause ill-health but, rather, to be a consequence of undetected underlying pre-existing ill-health not adjusted for (reverse causality).

“The study confirms that napping is associated with a greater risk. Napping could reflect underlying ill-health (fatigue, tiredness) eventually leading to morbidity and mortality, could be a proxy for sleep deprivation, as a compensatory catch-up mechanism, or could also be a symptom of circadian misalignment. The PURE study, not analysing in detail the interaction with short duration and not measuring quality of sleep and chronotypes, is unable to make further contributions to the field.”


‘Association of estimated sleep duration and naps with mortality and cardiovascular events: a study of 116,632 people from 21 countries’ by Chuangshi Wang et al. was published in European Heart Journal at 00:05 UK time on Wednesday 5th December.

 All our previous output on this subject can be seen at this weblink:


Declared interests

None received.

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