Less sleep linked to increased mortality in metabolic syndrome

By Bianca Nogrady
Short sleep duration may increase mortality risk in people with the metabolic syndrome, new research suggests.

In a prospective cohort study, researchers followed 1344 men and women for a mean of 16.6 years, after an initial in-laboratory sleep study. During the visit, various parameters were measured, including body mass index (BMI), blood pressure (BP), blood glucose and cholesterol levels.

The study, published in the Journal of the American Heart Association, found that participants with the metabolic syndrome who slept less than six hours a night had a significantly higher risk of all-cause mortality compared with those who slept six hours or more. This increased mortality risk associated with shorter sleep duration was more pronounced in participants with elevated BP and/or elevated fasting blood glucose. In these patients, there was an even stronger association between less than six hours sleep and increased cardiovascular or cerebrovascular mortality.

The increased all-cause and cardiovascular or cerebrovascular mortality was independent of other risk factors commonly associated with the metabolic syndrome, mortality or sleep dysfunction (such as age, sex, smoking or sleep apnoea).

The study authors noted that the effect appeared ‘primarily driven by the high BP and glucose dysregulation components of MetS [the metabolic syndrome], which indicates that objective short sleep duration in persons with MetS may be related to the degree of central autonomic and metabolic dysfunction.’

Associate Professor Garun Hamilton, Director of Sleep Medicine Research at Monash Health and Monash University in Melbourne, said the findings highlight the importance of adequate sleep, a risk factor that is often neglected as a target for intervention.

‘We talk a lot about the importance of good diet and regular physical activity but sleep often gets forgotten,’ said Professor Hamilton, who is also Clinical Chair of the Australasian Sleep Association.

‘I think as clinicians we need to aggressively target components of the metabolic syndrome, such as blood pressure and glucose control, but equally focus on people’s sleep quality and timing to improve outcomes as well.’

Professor Hamilton told Medicine Today that the results fit with short-term laboratory studies showing that sleep restriction is associated with insulin resistance and other metabolic abnormalities.
J Am Heart Assoc 2017; doi: 10.1161/JAHA.117.005479.

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