[Sleep disorders in elderly].

Insomnia affects 20% of the adult population in western countries and its prevalence increases with age. There is a controversy regarding the origin of sleep disorders in elderly. Are they only due to a senile process of sleep functioning or due to other associated comorbidities? Considering the objective assessment of sleep in elderly (by polysomnography), it has been shown an increasing sleep latency, decreasing total sleep time and sleep efficiency, a lower percentage of slow wave sleep. The circadian clock is also modified by age with phase advance and a decreased amplitude of the circadian rhythms. The most relevant comorbidities found in older people are: sleep apneas, restless leg syndrome, psychiatric disorders (anxiety and depression) and the use of drugs.