Longer sleep duration is related to increased pain sensitivity in healthy young men

Abstract

Introduction In recent years, evidence demonstrating that deprived and/or disturbed sleep increase sensitivity to pain, has been obtained both in clinical pain patient samples and in experimental protocols involving sleep deprivation and evoked pain in healthy subjects. However, sleep deprivation studies typically assess total/partial sleep deprivation in controlled laboratory conditions that bear little resemblance to the natural sleep environment. This study aimed to assess relationships between habitual sleep patterns, i.e., sleep duration, bedtime and wake-time, based on objective measurement in the home environment, and sensitivity to experimental pain in healthy subjects exposed to multi modal pain tests. It was hypothesized that increased sleep duration would be related to decreased sensitivity in different pain modalities. Materials and methods Forty-eight healthy men underwent experimental pain testing for four pain threshold measures: mechanical (pressure algometer), heat (thermal sensory analyzer) and cold (thermal sensory analyzer and cold bath), in the morning, early afternoon and evening, in a randomized order repeated measures design. Pain threshold scores were standardized and averaged to create a generic threshold score. Sleep patterns were assessed by actigraphy for seven days prior to testing. Pearson correlation coefficients were used to assess relationships between sleep patterns and pain thresholds. Results Longer sleep duration was associated with decreased pain thresholds (i.e., increased sensitivity) in mechanical pain in the afternoon and evening ( r = −.33 and r = −.31 respectively, p r = −.35 and r = −.31 respectively, p r = −.34 and r = −.35 respectively, p r = −.29, p r = −.41, p r = −.34, p Conclusion Unexpectedly, findings show that habitual longer sleep duration and later wake-time are associated with increased sensitivity in some pain modalities. Pending further investigation, it may be claimed that a U shaped relationship characterizes sleep duration and pain, with short and long sleepers demonstrating increased sensitivity to painful stimuli. Acknowledgement This study was supported by a grant of the Israel Pain Society .