Source: Pain  |  Posted 9 years ago

Poor sleep quality appears to account for the positive relationship between pain and fatigue in patients with fibromyalgia, suggesting a cyclical pattern of heightened pain and non-restful sleep.

Researchers at the California School of Psychology, in San Diego, California, United States, evaluated the predictors of fatigue in patients with fibromyalgia, using cross-sectional and daily assessment methods.

In a sample of 105 fibromyalgia patients, greater depression and lower sleep quality were found to be concurrently associated with higher fatigue. But, while pain was correlated with fatigue, regression analysis revealed that it did not independently contribute to fatigue.

However, for a subset of patients (n=63) who participated in a week of prospective daily assessment of their pain, sleep quality, and fatigue, multiple regression analysis revealed that previous day's pain and sleep quality predicted next day's fatigue.

An analytic model in which between-subject variability was removed and in which pain was predicted to contribute to lower sleep quality and greater fatigue revealed that poor sleep quality fully accounted for the positive relationship between pain and fatigue.

This substantiates the role of sleep quality in mediating pain and fatigue, the researches say. "The findings are indicative of a dysfunctional, cyclical pattern of heightened pain and non-restful sleep underlying the experience of fatigue in fibromyalgia," they conclude.