Sleeping More Than 8 Hours 'Linked to Early Death and CVD'

Peter Russell

August 10, 2018

People who sleep for more than 8 hours each night could be at a higher risk of dying prematurely and of developing cardiovascular disease (CVD) than those who sleep less, new research found.

The study, led by Keele University, found that sleeping for 9 hours had a 14% higher risk of dying from any cause, which rose to 30% for 10 hours and 47% for 11 hours. 

No significant difference was seen for people who slept for less than 7 hours, whereas similar patterns were observed for deaths from stroke and CVD.

Sleep 'A Marker of Ill Health'

"Prolonged sleep may be a marker for underlying cardiovascular risk or physical ill health," lead researcher Dr Chun Shing Kwok, a clinical lecturer in cardiology at Keele University, told Medscape UK.

The study, published in the Journal of the American Heart Association, drew on data from 74 international studies involving 3,340,684 participants.

The research also found that poor sleep quality was associated with a 44% increased risk of coronary heart disease but was not linked to other conditions.

The results suggested that sleeping for longer than the recommended duration of 7 or 8 hours may be associated with a moderate degree of harm, compared to those who slept for shorter times.

'Sleep is Complex'

"Sleep is complex and this study was not designed to assess the mechanisms of sleep on health," said Dr Kwok. "Abnormal sleep may be a marker of conditions such as obstructive sleep apnoea, hypothyroidism, anaemia, and heart failure.

"Sleep also affects hormones, mood, stress levels, blood pressure, appetite, and weight."

One limitation to the investigation, which included researchers from the University of Manchester, the University of Leeds and the University of East Anglia, was that sleep duration was assessed by self-reported questionnaires or direct questioning.

"One important message is that clinicians should take more consideration of patients' sleep duration and quality," said Dr Kwok. "Abnormal sleep may be a marker of elevated cardiovascular risk and patients with abnormal sleep should be assessed for possible underlying illness."

Self-Reported Sleep Duration and Quality and Cardiovascular Disease and Mortality: A Dose-Response Meta-Analysis, Journal of the American Heart Association. Paper.


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