A UK research review has found that people who sleep for more than eight hours a night have a greater mortality and cardiovascular risk than those who sleep for under seven hours.
A sleep duration of ten hours is linked with 30% increased risk of dying compared to sleeping for seven hours.
The study examined the link between self-reported sleep and cardiovascular disease and mortality in more than 3m participants. The research found that a sleep duration of ten hours is further linked to a 56% increased risk of stroke mortality and a 49% increased risk of cardiovascular disease mortality.
The researchers from Keele University, along with colleagues at The University of Manchester, the University of Leeds and the University of East Anglia, reviewed 74 studies looking at mortality and cardiovascular outcomes by self-reported sleep duration and sleep quality. The study also found that poor sleep quality was associated with a 44% increase in coronary heart disease.
Lead researcher Dr Chun Shing Kwok, working with Professor Mamas Mamas at Keele University's Institute for Science and Technology in Medicine, explains: “Our study has an important public health impact in that it shows that excessive sleep is a marker of elevated cardiovascular risk.
“Our findings have important implications as clinicians should have greater consideration for exploring sleep duration and quality during consultations. If excessive sleep patterns are found, particularly prolonged durations of eight hours or more, then clinicians should consider screening for adverse cardiovascular risk factors and obstructive sleep apnoea, which is a serious sleep disorder that occurs when a person's breathing is interrupted during sleep.”
The analysis suggests that excessive sleep patterns are a marker of increased cardiovascular risk. The results show that sleeping for longer than the recommended duration of seven or eight hours may be associated with a moderate degree of harm, compared to those who sleep for shorter durations.
Kwok added: “The important message is that abnormal sleep is a marker of elevated cardiovascular risk and greater consideration should be given in exploring both duration and sleep quality during patient consultations.
“Sleep affects everyone. The amount and quality of our sleep is complex. There are cultural, social, psychological, behavioural, pathophysiological and environmental influences on our sleep such as the need to care for children or family members, irregular working shift patterns, physical or mental illness, and the 24-hour availability of commodities in modern society.
“This research began because we were interested to know if it was more harmful to sleep below or beyond the recommended sleep duration of seven to eight hours. We further wanted to know how incremental deviation from recommended sleep duration altered risk of mortality and cardiovascular risk.”
Background: There is growing evidence that sleep duration and quality may be associated with cardiovascular harm and mortality.
Methods and Results: We conducted a systematic review, meta‐analysis, and spline analysis of prospective cohort studies that evaluate the association between sleep duration and quality and cardiovascular outcomes. We searched MEDLINE and EMBASE for these studies and extracted data from identified studies. We utilized linear and nonlinear dose‐response meta‐analysis models and used DerSimonian–Laird random‐effects meta‐analysis models of risk ratios, with inverse variance weighting, and the I2 statistic to quantify heterogeneity. Seventy‐four studies including 3 340 684 participants with 242 240 deaths among 2 564 029 participants who reported death events were reviewed. Findings were broadly similar across both linear and nonlinear dose‐response models in 30 studies with >1 000 000 participants, and we report results from the linear model. Self‐reported duration of sleep >8 hours was associated with a moderate increased risk of all‐cause mortality, with risk ratio, 1.14 (1.05–1.25) for 9 hours, risk ratio, 1.30 (1.19–1.42) for 10 hours, and risk ratio, 1.47 (1.33–1.64) for 11 hours. No significant difference was identified for periods of self‐reported sleep <7 hours, whereas similar patterns were observed for stroke and cardiovascular disease mortality. Subjective poor sleep quality was associated with coronary heart disease (risk ratio, 1.44; 95% confidence interval, 1.09–1.90), but no difference in mortality and other outcomes.
Conclusions: Divergence from the recommended 7 to 8 hours of sleep is associated with a higher risk of mortality and cardiovascular events. Longer duration of sleep may be more associated with adverse outcomes compared with shorter sleep durations.
Chun Shing Kwok, Evangelos Kontopantelis, George Kuligowski, Matthew Gray, Alan Muhyaldeen, Christopher P Gale, George M Peat, Jacqueline Cleator, Carolyn Chew‐Graham, Yoon Kong Loke, Mamas Andreas Mamas
[link url="https://www.keele.ac.uk/discover/news/2018/august/peoplewhosleepmorethaneighthourshavegreatermortalityandcardiovascularrisk/have-greater-mortality-cardiovascular-risk.php"]Keele University material[/link]
[link url="https://www.ahajournals.org/doi/10.1161/JAHA.118.008552"]Journal of the American Heart Association abstract[/link]