Background & Aims

Although a robust connection between sleep and pain is established [1], the extent to which circadian rest-activity rhythms contribute toward unique variations in pain, beyond what is elucidated by sleep, remains uncertain [2]. Furthermore, it is largely unknown whether daily sleep and circadian rest-activity rhythms have interactive effects on pain experiences. This study aimed to bridge these critical research gaps by combining wrist actigraphy and daily diary data, offering new insights into these dynamics in a sample of women with temporomandibular joint disorders and insomnia symptoms

Methods

We assessed sleep and circadian rest-activity rhythms in 140 women with temporomandibular joint disorders and insomnia symptoms, using 14-days of 24-hour wrist actigraphy. Average pain severity (0-10 Numerical Rating Scale) was also assessed nightly before participants went to bed, over the same 14-day period. Sleep variables included Total Sleep Time (TST) and Wake After Sleep Onset (WASO). Circadian variables were Relative Amplitude (i.e., with higher amplitude indicating strength/robustness of individual’s rest-activity rhythm), and Intradaily Variability (i.e., with greater variability representing more fragmentation of the 24 hours rhythm). Linear mixed-effects modeling was employed to first examine how sleep and circadian disturbances predict next-day pain severity, and in the second step, to investigate their interaction effects.

Results

The mean age of the participants was 37 (SD = 11), and most of them self-identified as White (75%). When all sleep and circadian variables were included in the same model, both TST (b = -.12, p = .002) and WASO (b = .20, p = .002) from the previous night, along with relative amplitude (b = -2.75, p < .001) from the past 24 hours, significantly predicted next-day pain severity. Specifically, greater TST and amplitude were associated with lower next-day pain, while higher WASO was associated with greater next-day pain. When we examined interaction effects, we found that Intradaily Variability significantly moderated the relationship between WASO and next-day pain severity (b = 1.29, p = .010); on days characterized by greater fragmentation in the circadian rest-activity rhythm, the positive association between previous night WASO and next-day pain severity intensified.

Conclusions

This study underscores that both sleep and circadian rest-activity rhythms are associated with daily pain experiences. Importantly, the significant interaction between sleep and circadian variables indicates that circadian rhythm fragmentation may exacerbate the effect of sleep continuity disturbances on pain. The present study advances our understanding of the complex interplay between sleep, circadian rest-activity rhythms, and pain, offering potential avenues for targeted interventions.

References

1. Finan PH, Goodin BR, Smith MT. The association of sleep and pain: an update and a path forward. J Pain. 2013;14(12):1539-1552.
2. Mun CJ, Burgess HJ, Sears DD, et al. Circadian Rhythm and Pain: a Review of Current Research and Future Implications. Curr Sleep Med Reports. 2022:1-10.

Presenting Author

Chung Jung Mun

Poster Authors

Chung Jung Mun

Ph.D.

Arizona State University

Lead Author

E-mail

Patrick H Finan. PhD

University of Virginia, Charlottesville

Lead Author

E-mail

Siny Tsang

Ph.D.

University of Virginia School of Medicine

Lead Author

E-mail

Matthew Reid

Ph.D.

Johns Hopkins School of Medicine

Lead Author

E-mail

Jennifer Haythornthwaite

United States Association for the Study of Pain

Lead Author

E-mail

Michael T Smith PhD CBSM

Johns Hopkins School of Medicine

Lead Author

E-mail

Topics

  • Mechanisms: Psychosocial and Biopsychosocial