Update on sleep and its disorders.

Inadequate sleep and sleep disorders have important adverse consequences on multiple systems. This review covers three areas: (a) Genetic determinants of sleep disorders. Common gene variants with small effects have been identified for both restless legs syndrome and narcolepsy with cataplexy. Rare variants with large effects have been found in familial phase advance syndrome and in subjects with short sleep durations. (b) Obstructive sleep apnea (OSA). OSA is an oxidative stress disorder. Prospective cohort studies show an increased risk of cardiovascular events in patients with untreated severe OSA. (c) The impact of sleep disorders on obesity and diabetes. Inadequate sleep results in changes in insulin resistance and in hormone levels leading to increases in appetite. Hence, inadequate sleep is associated with development of obesity. OSA is also an independent risk factor for insulin resistance; treatment of OSA can improve insulin sensitivity.