Objective: Sleep disturbances are common in fibromyalgia (FM) and have been suggested to be an early feature of the syndrome, but may also be a consequence of pain. The aim of this study was to evaluate whether sleep disturbances predicted the development of chronic widespread pain (CWP).
Methods: A representative sample of 3928 subjects aged 20-74 years from the general population was sent a questionnaire in 1995. Of those initially responding (n=2425), 79% responded to a follow up questionnaire in 1998. From a manikin with predefined body regions subjects were classified as having CWP according to 1990 ACR criteria for FM, having chronic regional pain (CRP) or no chronic pain (NCP). Four modalities of sleep disturbances were assessed: difficulty in falling asleep, frequent awakenings, early awakenings and not feeling rested. Sleep problems were graded no/small, moderate and large/very large and were in the analyses controlled for age, gender and amount of pain at baseline.
Results: The frequencies of large/very large sleep disturbances at baseline in the groups with NCP, CRP and CWP were for difficulty falling asleep (3.6%, 8.7%, 18.0%), frequent awakenings (5.4%, 13.6%, 26.3%), early awakenings (4.2%, 10.5%, 25.5%) and not feeling rested (6.2%, 12.3%, 32.5%). In those with NCP or CRP at baseline the development of CWP was predicted by having large/very large problems with frequent awakenings (OR=1.9; 95% CI 1.0-3.7), early awakenings (OR=2.1; 95% CI 1.1-4.2), and not feeling rested (OR=2.2; 95% CI 1.1-4.3) compared to having small/no problems.
Conclusion: Frequent awakenings, early awakenings and not feeling rested precede the development of CWP. The results are compatible with the hypothesis that non-restorative sleep is a pathogenic factor for the development of chronic widespread pain.