Insomnia: prevalence, impact, pathogenesis, differential diagnosis, and evaluation.

When patients report problems sleeping, a psychiatrist must determine their significance based on frequency, duration, and daytime impairment. Because up to 50% of adults report sleep problems in any year, it is necessary to define when insomnia becomes long-standing, severe, and a complication to daytime function. Psychiatrists must determine if a sleep disturbance reduces mood, motor performance, or cognitive function. If insomnia syndrome is present, major depression, dysthymia, and anxiety disorders commonly are comorbid. To assist in evaluating insomnia, psychiatrists are urged to use the 6 Ps + M of insomnia model to conceptualize the characteristics of the insomnia and coordinate therapeutic intervention.