Relationships Between Sleep Quality and Pain-Related Factors for People with Chronic Low Back Pain: Tests of Reciprocal and Time of Day Effects

Abstract

Background: Poor sleep quality among people with chronic low back pain appears to be related to worse pain, affect, poor physical function, and pain catastrophizing. The causal direction between poor sleep and pain remains an open question, however, as does whether sleep quality exerts effects on low back pain differently across the course of the day.

Purpose: This daily diary study examined lagged temporal associations between prior night sleep quality and subsequent day pain, affect, physical function and pain catastrophizing, the reverse lagged temporal associations between prior day pain-related factors and subsequent night sleep quality, and whether the time of day during which an assessment was made moderated these temporal associations.

Methods: Chronic low back pain patients (n = 105) completed structured electronic diary assessments five times per day for 14 days. Items included patient ratings of their pain, affect, physical function, and pain catastrophizing.

Results: Collapsed across all observations, poorer sleep quality was significantly related to higher pain ratings, higher negative affect, lower positive affect, poorer physical function, and higher pain catastrophizing. Lagged analyses averaged across the day revealed that poorer prior night sleep quality significantly predicted greater next day patient ratings of pain, and poorer physical function and higher pain catastrophizing. Prior poorer night sleep quality significantly predicted greater reports of pain, and poorer physical function, and higher pain catastrophizing, especially during the early part of the day. Sleep quality × time of day interactions showed that poor sleepers reported high pain, and negative mood and low function uniformly across the day, whereas good sleepers reported relatively good mornings, but showed pain, affect and function levels comparable to poor sleepers by the end of the day. Analyses of the reverse causal pathway were mostly nonsignificant.

Conclusions: Sleep quality appears related not only to pain intensity but also to a wide range of patient mood and function factors. A good night's sleep also appears to offer only temporary respite, suggesting that comprehensive interventions for chronic low back pain not only should include attention to sleep problems but also focus on problems with pain appraisals and coping.

Keywords: Chronic low back pain; Daily diary; Lagged relationships; Negative affect; Pain; Pain catastrophizing; Physical function; Positive affect; Sleep quality.

Figure 1

Link between Sleep Quality and Subsequent Pain Intensity is Moderated by Time of Day. Sleep quality refers to within-subject changes in sleep quality. Poor sleep (solid line) is identified as one Standard Deviation below the average person centered mean. Good sleep (dashed line) is identified +1 SD refers to one Standard Deviation above the average person centered mean. Good sleep (dashed line) is associated lower pain intensity in the morning hours, but this pain intensity increases over the course of the day.

Figure 2

Link between Sleep Quality and Subsequent Pain Catastrophizing is Moderated by Time of Day. Sleep quality refers to within-subject changes in sleep quality. Poor sleep (solid line) is identified as one Standard Deviation below the average person centered mean. Good sleep (dashed line) is identified +1 SD refers to one Standard Deviation above the average person centered mean. Good sleep (dashed line) is associated lower pain catastrophizing in the morning hours, but this pain catastrophizing increases over the course of the day.

Figure 3

Link between Sleep Quality and Subsequent Negative Affect is Moderated by Time of Day. Sleep quality refers to within-subject changes in sleep quality. Poor sleep (solid line) is identified as one Standard Deviation below the average person centered mean. Good sleep (dashed line) is identified +1 SD refers to one Standard Deviation above the average person centered mean. Good sleep (dashed line) is associated lower negative in the morning hours, but this negative affect increases over the course of the day.

Figure 4

Link between Sleep Quality and Subsequent Pain Interference is Moderated by Time of Day. Sleep quality refers to within-subject changes in sleep quality. Poor sleep (solid line) is identified as one Standard Deviation below the average person centered mean. Good sleep (dashed line) is identified +1 SD refers to one Standard Deviation above the average person centered mean. Good sleep (dashed line) is associated lower pain interference in the morning hours. Pain interference increases over the course of the day for both groups.