Study Objectives: To investigate changes over 15 years in the prevalence of insomnia and its association with demographic characteristics and hypnotic medication use. Design: Analysis of 3 cross-sectional national mental health surveys carried out in 1993, 2000, and 2007, which used comparable sampling methods and identical insomnia assessments. Setting: Adults living in private households in England. Patients or Participants: 20,503 people aged 16-64 years. Measurements and Results: Insomnia was defined according to 4 different criteria, using relevant questions from the revised Clinical Interview Schedule. Modest increases in insomnia prevalence were found over the survey periods (any symptoms increasing from 35.0% in 1993 to 38.6% in 2007; insomnia diagnosis from 3.1% to 5.8%, respectively). In all 3 surveys, similar strengths of association in relation to all criteria were found, with female gender, increased age, lower educational attainment, depression, unemployment, economic inactivity, and widowed, divorced, or separated status. Prevalence of hypnotic use was double in 2000 (0.8%) compared to 1993 (0.4%); from limited information on selected medications, there was no such increase between 2000 and 2007. The reasons reported for any sleep disturbance over the last month were generally similar across surveys, the most marked change being illness/discomfort increasing as an explanation from 14.3% to 17.4% to 19.0%. Conclusions: In the English general population, insomnia (by any definition) showed a modest but steady increase in prevalence over a 15-year period. Strengths of associations with demographic factors and self-reported reasons for sleep disturbance remained reasonably stable over this period. Citation: