Assessment and management of insomnia.

Insomnia has a major impact on human health, performance, economic productivity and quality of life.1,2 Insomnia chronic or severe enough to merit treatment occurs in 8–14% of the general population.3 There are few specialised sleep clinics in Great Britain other than respiratory ones (eg for obstructive sleep apnoea syndrome (OSAS)), most clinicians do not have easy access to psychological treatments, and very often the simplest course of action is the prescription of hypnotic drugs. However, the appropriate use of hypnotics requires an accurate diagnosis of the sleep disorder and knowledge of the pharmacokinetics and dynamics of the available drugs. The length of total sleep in a day varies in normal adults, with an average of 7–8 hours in the 20–45 year age group. Sleep time and sleep continuity are decreased in older people and increased daytime napping often leads to a further reduction in the night-time sleep. A normal subject has several short awakenings during the night, most of which are not perceived as awakenings unless they last more than about two minutes. There will probably not be clear consciousness, but subjects may have occasional brief thoughts of how comfortable they feel or how pleased they are that it is not yet time to get up, with an immediate return to sleep. If during the short period of waking some factor causes anxiety or anger (eg aircraft noise, partner’s snores or dread of being awake), progress to full awakening and remembering this awakening in the morning are much more likely. The more often this happens, the more subjects complain of unrefreshing sleep. Perhaps the most common cause of irritation derives from ‘clock watching’: subjects check the time on awakening, remember it and repeat this cycle many times during the night, neglecting periods of sleep in between. This produces anger and frustration, which in turn delay return to sleep and may promote subsequent awakenings.