The Problem of Long-Term Insomnia: a 5-Year Follow-Up Study in a Middle-Aged Population

The prevalence of insomnia has been studied in many populations with different definitions of insomnia. The International Classification of Sleep Disorders (1) defines insomnia also in its mildest form as an almost nightly complaint of an insufficient amount of sleep, or not feeling rested after the habitual sleep episode. The severity of insomnia is determined by the impairment of social and occupational functioning. In a recently published large epidemiological study where the DSM-IV criteria were used for the definition of insomnia the prevalence of insomnia was 18.6% (14.0% for men and 22.8% for women, age over 18 years) and severe insomnia was found in 9.3% (6.3% of men and 12.0% of women) (2). In most studies the numbers of insomniacs are higher among women than men and the prevalence increases with age. Most studies concern acute complaints or The Problem of Long-Term Insomnia: a 5-Year Follow-Up Study in a Middle-Aged Population