RESUMEN
Seasonal variability has been detected in a variety of illnesses. The purpose of this study is to examine seasonal variability in pain intensity, demoralization and range of mandibular motion among patients suffering from myofascial face pain. Pain and demoralization for cases (n = 140) and demoralization for controls (n = 133) were measured in each of 10 monthly interviews. Range of motion was measured once only for cases. Their pain intensity (P < 0.009) and demoralization (P < 0.04) were significantly greater in the peak dark months than in the peak light months. There was a non-significant trend (P < 0.07) toward elevated demoralization in the darker months for controls. Range of motion, assessed cross-sectionally, did not demonstrate a seasonal pattern. These data support our prior finding that myofascial face pain and depressed mood are co-morbid and may be maintained by common risk factors.