Objective. Sleep problems are common among patients with fibromyalgia (FM). However, it is not known whether poor sleep is a contributing factor in FM or a consequence of the illness. The aim of the current study was to prospectively investigate the association between self-reported sleep problems and risk of FM among adult women.Methods. We longitudinally studied 12,350 women who did not have FM, musculoskeletal pain, or physical impairments at baseline (1984)(1985)(1986) Conclusion. These prospective data indicate a strong dose-dependent association between sleep problems and risk of FM. The association is somewhat, although not significantly, stronger in middle-aged and older women than in younger women.Fibromyalgia (FM) is a chronic musculoskeletal pain syndrome with a complex etiology. The prevalence of FM in the general adult population is ϳ3-5%, with a predominance among women (1). Disturbed sleep (e.g., insomnia and nocturnal awakening) and undue fatigue due to nonrestorative sleep are common comorbid symptoms in patients with FM (2,3). Self-reported sleep problems in patients with FM have been substantiated by polysomnographic recordings, showing alterations in sleep architecture and electroencephalographic sleep pattern, in some but not all studies (4). Whether poor sleep is a contributing factor in the development of FM or, rather, develops as a consequence of the illness is currently not known. We prospectively studied a large and unselected population of women who did not have FM, musculoskeletal pain, or physical impairment at baseline, to investigate whether sleep problems increase the risk of FM development.
PATIENTS AND METHODSStudy population. The (Helseundersøkelsen i NordTrøndelag [Nord-Trøndelag Health Study] [HUNT study]) is a collaborative effort of the HUNT Research Centre at the Norwegian University of Science and Technology, the NordTrøndelag (Norway) County Council, and the Norwegian Institute of Public Health. All residents of Nord-Trøndelag County age Ն20 years were invited to participate in 2 separate phases of the HUNT study: first in 1984-1986 (HUNT 1) and then in 1995-1997 (HUNT 2). Among 42,568 women who were eligible, 38,274 (89.9%) accepted the invitation to participate in the HUNT 1 and completed a questionnaire that was sent with the invitation. A clinical examination was conducted, at which body mass and height were measured and the women were given a second questionnaire to complete at home and return in a prestamped envelope. For the HUNT 2, 46,709 women were invited to participate, and 34,518 (73.9%) accepted the invitation. The procedures were similar to those described for the HUNT 1, although both the questionnaires and the clinical examination were more comprehensive.There were 24,357 women who participated in both the HUNT 1 and the HUNT 2, and these women were selected for the present study. Of these 24,357 women, we excluded 6,093