INVITED COMMENTARY

Circadian Disruption—a New Direction for Psycho-oncologyResearch? A Comment on Dedert et al.

Laura S. Porter, PhD

Published online: 15 May 2012# The Society of Behavioral Medicine 2012

The development of biobehavioral models of cancer has ledto increasingly sophisticated studies regarding the role ofpsychological factors in the onset and progression of cancer.The present study by Dedert and colleagues [1], guided by amodel of circadian effects of cancer progression [2], exam-ined associations between psychological responses and dis-ruptions in circadian rest/activity and cortisol rhythms inwomen newly diagnosed with cancer. Circadian disruptionshave been linked to poorer quality of life as well as earlymortality in patients with metastatic cancer [3–5] but havenot been widely studied in nonmetastatic populations.

Findings from this study indicated that women whoreported more intrusive thoughts and avoidant coping dis-played circadian disruptions including daytime inactivityand inconsistent activity patterns. In addition, those withmore disruptions in their activity/rest cycles had flatteneddiurnal cortisol rhythms. However, psychological variableswere not related to cortisol disruptions (a finding consistentwith several prior studies [6–8]). Given the small samplesize and cross-sectional design of this study, these findingsshould be considered preliminary. However, they do suggestthe possibility that psychological responses at the time ofcancer diagnosis are associated with disruptions in circadianrhythms, which could influence disease progression.

The methodology used to collect saliva samples andverify their timing is a particular strength of this study andshould serve as a model for future research. Collection ofsalivary cortisol took place four times per day to captureboth cortisol response to wakening and the diurnal slope.Importantly, the timing of the samples was verified using

electronic MEMS caps, and bedtime and wake times werecorroborated using actigraphy data. The close attention tothe timing of the samples is critical; prior research indicatesthat noncompliance with sample collection times has asignificant effect on cortisol diurnal rhythms and responseto wakening [9].

Another notable strength of this study is the diversity ofthe participants. Two thirds of the participants wererecruited from a cancer center that primarily serves low-income patients, and over one third of the participants wereAfrican-American. In contrast, the majority of previousstudies examining cortisol in cancer patients have beenconducted with samples consisting of predominantly Cau-casian subjects [6, 7, 10, 11]. In a recent study, we foundthat African-American cancer survivors had significantlyflatter diurnal slopes than Caucasians [12]. Studies of com-munity samples have also found that cortisol levels anddiurnal slopes differ by race and SES (e.g., [13]). Further-more, in the current study, women with lower incomereported higher levels of intrusive thoughts and avoidantcoping and greater rest/activity disruption. Taken together,these findings indicate the importance of including econom-ically and racially diverse samples.

As noted above, the findings of this study are preliminary.However, they are intriguing and suggest several avenues forfuture research. First, it is plausible that there are bidirectionalrelationships between psychological responses to cancer andactivity/rest rhythms. Longitudinal studies that measure bothconstructs over multiple phases of cancer survivorship (e.g.,diagnosis, active treatment, survivorship, recurrence) couldelucidate the nature of these associations and provide insightregarding the optimal timing and content of interventions tofacilitate positive adaptation. Second, longitudinal studies arenecessary to answer the critical question regarding the role ofcircadian disruption in disease progression. Third, if proven

L. S. Porter (*)Duke University Medical Center,Box 90399, Durham, NC 27708, USAe-mail: laura.porter@duke.edu

ann. behav. med. (2012) 44:1–2DOI 10.1007/s12160-012-9376-3

robust, these findings suggest that interventions should spe-cifically target activity/rest disruptions. Possibilities includechronobiotics such as melatonin [14], cognitive-behavioralinterventions for insomnia [15], and exercise therapy [16].Components of psychosocial interventions for stress manage-ment could also be adapted to target circadian rhythm regula-tion. For example, social support strategies could focus on therole of friends and family in encouraging regular activity, andrelaxation training could emphasize its benefits on sleep.

Conflict of Interest Statement The author has no conflict of interestto disclose.

References

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16. Jones LW, Peppercorn J, Scott JM, Battaglini C. Exercise therapyin the management of solid tumors. Curr Treat Options Oncol.2010;11(1–2):45–58.

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