Sleep & the metabolic syndrome.

Sleep is an essential part of our daily living, and sleep disturbances may intervene with the biological and physiological processes in human body leading to the development of metabolic dysfunction. Short sleep duration and poor sleep quality have adverse effects on metabolism and hormonal processes, contributing to increased cardiovascular risk. Obstructive sleep apnoea is a chronic condition characterized by repetitive upper airway collapse during sleep, causing intermittent hypoxaemia, recurrent arousals and sleep fragmentation. Sleep disturbances can increase sympathetic activity, provoke systemic inflammation and oxidative stress, and impair vascular endothelial function. Obstructive sleep apnoea is increasingly recognized to be an independent cardiovascular risk factor. There is intense research interest in the association between obstructive sleep apnoea and the metabolic syndrome - the constellation of inter-related metabolic derangements including central obesity, hypertension, insulin resistance and dyslipidaemia, which appears to directly promote the development of atherosclerosis. The underlying pathophysiologic pathways or mechanistic links between obstructive sleep apnoea and metabolic syndrome have not been well delineated. This article reviews the current knowledge of the relationship between sleep disturbances, sleep-disordered breathing and the metabolic syndrome in adults.

Obstructive sleep apnoea: Definitions, epidemiology & natural history.

Obstructive sleep apnoea (OSA) is increasingly being recognized as an important health issue in the last two to three decades. It is characterized by frequent episodes of upper airway collapse during sleep, causing recurrent arousals, intermittent hypoxaemia, sleep fragmentation and poor sleep quality. There is accumulating evidence that OSA is being considered as an independent risk factor for hypertension, glucose intolerance / diabetes mellitus, cardiovascular diseases and stroke, leading to increased cardiometabolic morbidity and mortality. The prevalence rates of OSA have been estimated in the range of 2 to 10 per cent worldwide, and the risk factors for obstructive sleep apnoea include advanced age, male sex, obesity, family history, craniofacial abnormalities, smoking and alcohol consumption. The common clinical presenting symptoms are heavy snoring, witnessed apnoeas and daytime hypersomnolence, which would help to identify the affected individuals. With increasing awareness of this disease entity and associated complications in our society, there have been increased referrals to sleep physicians or expertise for further investigations and diagnostic evaluation. Early recognition and treatment of obstructive sleep apnoea may prevent from adverse health consequences. some of the epidemiological aspects of obstructive sleep apnoea in adults are reviewed.