[Sleep and aging].
A COMMON DISORDER: Sleep is one of the most often altered functions in elderly people. Obviously, insomnia is one of the main complain, inducing benzodiazepine (BSD) abuse, but we must keep in mind that sleep apnoea syndrome (SAS) and restless legs syndrome (RLS) are also frequent in this group of age. After exclusion of the various age-related conditions that could induce sleep disorders, we must focalise on primary and secondary sleep disorders. As an introduction, methods of sleep analysis are described and qualitative and quantitative sleep variables are given. PHYSIOLOGICAL SLEEP: Comparing the sleep of elderly people to the one of young adult give us the opportunity to define the limits of the physiological sleep aging. It seems that the main age-induced sleep disturbances are problems to maintain sleep and chronobiological disorganisation of the sleep-wake rhythm, both responsible for insomnia complains. It is important to note that SAS and RLS prevalence are correlated with age. Also crucial is the complex association between sleep, depression and dementia. These interactions are addressed from a diagnostic and a therapeutic point of view. THERAPEUTIC APPROACH: Lastly, concerning insomnia we emphasise the importance of therapeutic alternative to BZD, responsible for addictions and cognitive impairment, mainly behavioural and chronotherapeutic methods (phototherapy, melatonin). For clinicians, it is recommended to respect the individual rhythms of each elderly patient and to prefer nonpharmacological methods.