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Minimum of five hours’ sleep for good health and longevity – UK study

Researchers say chances of multiple chronic health problems in people older than 50, could be reduced if they have a minimum of five hours sleep a night, adding that ill health might disrupt sleep, but poor sleep can be a forewarning or risk itself.

Although there is evidence that sleep helps restore, rest and rejuvenate the body and mind, why the “golden slumber number” might matter remains unclear, according to a PLOS Medicine study that tracked the health and sleep of UK civil servants.

The 8 000 participants were asked: How many hours of sleep do you have on an average weeknight?

They were checked for chronic conditions, including diabetes, cancer and heart disease, over two decades of follow-up, and those who slept for five hours or less around the age of 50 had a 30% greater risk of multiple ailments than those who slept seven hours.

Shorter sleep at 50 was also associated with a higher risk of death during the study period, mainly linked to the increased risk of chronic disease.

Experts generally recommend about seven or eight hours, said the researchers, from University College London and Paris Cité University.

Why do we sleep?

Scientists do not know for sure, but it is clear that sleep helps the brain process memories and is good for mood, concentration and metabolism. It is also an opportunity for the brain to be cleared of waste.

Surrey Sleep Centre director Prof Derk-Jan Dijk told BBC News: “This work reinforces that getting only short sleep is not good for us. Generally, it’s not healthy, although for some, it may be OK.

“The big question is why do some people sleep less. What is causing it and is there anything we can do about it? Sleep is a modifiable lifestyle factor to a certain extent.”

Long stretches of bad sleep can also severely affect well-being.

GPs now rarely prescribe sleeping pills, which can have serious side-effects and cause dependency. But sleep problems can often be resolved and support is available.

Study details

Association of sleep duration at age 50, 60, and 70 years with risk of multimorbidity in the UK: 25-year follow-up of the Whitehall II cohort study

Séverine Sabia ,Aline Dugravot, Damien Léger, Céline Ben Hassen, Mika Kivimaki, Archana Singh-Manoux

Published in PLOS Medicine on 18 October 2022

Abstract

Background
Sleep duration has been shown to be associated with individual chronic diseases but its association with multimorbidity, common in older adults, remains poorly understood. We examined whether sleep duration is associated with incidence of a first chronic disease, subsequent multimorbidity and mortality using data spanning 25 years.

Methods and findings
Data were drawn from the prospective Whitehall II cohort study, established in 1985 on 10,308 persons employed in the London offices of the British civil service. Self-reported sleep duration was measured 6 times between 1985 and 2016, and data on sleep duration was extracted at age 50 (mean age (standard deviation) = 50.6 (2.6)), 60 (60.3 (2.2)), and 70 (69.2 (1.9)). Incidence of multimorbidity was defined as having 2 or more of 13 chronic diseases, follow-up up to March 2019. Cox regression, separate analyses at each age, was used to examine associations of sleep duration at age 50, 60, and 70 with incident multimorbidity. Multistate models were used to examine the association of sleep duration at age 50 with onset of a first chronic disease, progression to incident multimorbidity, and death. Analyses were adjusted for sociodemographic, behavioural, and health-related factors.

A total of 7,864 (32.5% women) participants free of multimorbidity had data on sleep duration at age 50; 544 (6.9%) reported sleeping ≤5 hours, 2,562 (32.6%) 6 hours, 3,589 (45.6%) 7 hours, 1,092 (13.9%) 8 hours, and 77 (1.0%) ≥9 hours. Compared to 7-hour sleep, sleep duration ≤5 hours was associated with higher multimorbidity risk (hazard ratio: 1.30, 95% confidence interval = 1.12 to 1.50; p < 0.001). This was also the case for short sleep duration at age 60 (1.32, 1.13 to 1.55; p < 0.001) and 70 (1.40, 1.16 to 1.68; p < 0.001). Sleep duration ≥9 hours at age 60 (1.54, 1.15 to 2.06; p = 0.003) and 70 (1.51, 1.10 to 2.08; p = 0.01) but not 50 (1.39, 0.98 to 1.96; p = 0.07) was associated with incident multimorbidity. Among 7,217 participants free of chronic disease at age 50 (mean follow-up = 25.2 years), 4,446 developed a first chronic disease, 2,297 progressed to multimorbidity, and 787 subsequently died. Compared to 7-hour sleep, sleeping ≤5 hours at age 50 was associated with an increased risk of a first chronic disease (1.20, 1.06 to 1.35; p = 0.003) and, among those who developed a first disease, with subsequent multimorbidity (1.21, 1.03 to 1.42; p = 0.02). Sleep duration ≥9 hours was not associated with these transitions. No association was found between sleep duration and mortality among those with existing chronic diseases. The study limitations include the small number of cases in the long sleep category, not allowing conclusions to be drawn for this category, the self-reported nature of sleep data, the potential for reverse causality that could arise from undiagnosed conditions at sleep measures, and the small proportion of non-white participants, limiting generalisation of findings.

Conclusions
In this study, we observed short sleep duration to be associated with risk of chronic disease and subsequent multimorbidity but not with progression to death. There was no robust evidence of an increased risk of chronic disease among those with long sleep duration at age 50. Our findings suggest an association between short sleep duration and multimorbidity.

 

PLOS Medicine article – Association of sleep duration at age 50, 60, and 70 years with risk of multimorbidity in the UK: 25-year follow-up of the Whitehall II cohort study (Open access)

 

BBC News article – Five hours’ sleep is tipping point for bad health (Open access)

 

See more from MedicalBrief archives:

 

How you sleep could be ‘strongest predictor’ of when you will die – US study

 

Seven hours is ideal amount of sleep in middle-age and older – UK-China study

 

Exposure to light during sleep linked to health risks – Chicago study

 

Sleep health problems significantly increase heart disease risk – South Florida University

 

 

 

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