Poor sleep and depression are independently associated with a reduced pain threshold. Results of a population based study.

To determine the relative contributions of psychological factors and sleep disturbance to reduced pain threshold we conducted a cross-sectional two-phase population-based study. A total of 424 subjects were recruited, stratified by pain and distress status. Subjects completed a postal questionnaire that asked about current pain and covered aspects of psychological status and sleep disturbance. Samples of subjects stratified by the extent of bodily pain they reported and psychological status were invited to participate in an examination of pain threshold. The association between psychological status, sleep disturbance and a low pain threshold was examined using ordinal regression. High levels of psychological distress (OR=1.6, 95% CI (1.02, 2.5)), disturbed sleep (OR=2.2, 95% CI (1.4, 3.5)) and high scores on the HAD depression scale (OR=2.1, 95% CI (1.3, 3.2)) were all associated with having a low pain threshold. In multivariate analysis disturbed sleep and depression remained independently associated with a low pain threshold. These relationships persisted after adjustment for pain status. This study had demonstrated that depression and poor sleep are associated with a reduced pain threshold.