The Diagnostic and Statistical Manual of Mental Disorders defines primary insomnia as a complaint lasting for at least one month of difficulty initiating and/or maintaining sleep or of nonrestorative sleep. The International Classification of Sleep Disorders-Revised (ICSD-R) uses the term "psychophysiologic insomnia" for such a complaint and associated decreased functioning during wakefulness. ICSD-R regards insomnia of 6-month duration as chronic. Both systems differentiate insomnia from circadian rhythm disorders, in which timing of the major sleep period is out of alignment with the local clock; from parasomnias, in which behavioral events occur in association with sleep (e.g., sleepwalking, night terrors); and from secondary insomnias, in which psychiatric, neurologic, or medical problems present. Disorders such as sleep apnea, with associated respiratory impairment, and disorders of excessive sleepiness (e.g., narcolepsy) are also classified separately.
Conservative estimates for chronic insomnia range from 9-12% in adulthood and up to 20% in later life, and women present about two times more than men. Sleep disturbance is a common complaint in general practice and once established may persist over many years. Insomnia therefore constitutes a considerable public health problem. The direct costs of assessing and treating insomnia were approximated as $14 billion in the United States and FF10 billion in France in 1995. (Am. Sleep Disorders Assoc. 1997)
Polysomnographic assessment (PSG) comprises monitoring of the electroencephalogram (EEG) along with muscle activity, eye movement, respiration, and blood oxygen saturation levels. However, PSG is not required unless clinical presentation raises the possibility of disorders such as sleep apnea. Actigraphic assessment is helpful to identify disorders of circadian function. The wrist actigraph provides data on body movement over extended periods (typically 1 minute epochs for several weeks) and is a reliable index of sleep parameters.
In practice, structured interview is recommended, supplemented by a sleep diary completed upon waking, comprising information on sleep-onset latency (SOL), wake time after sleep-onset, and total sleep time.................
