Contribution of cancer symptoms, dysfunctional sleep related thoughts, and sleep inhibitory behaviors to the insomnia process in breast cancer survivors: a daily process analysis.

INSOMNIA IS A PREVALENT AND DISTRESSING ISSUE FOR BREAST CANCER PATIENTS.1–6 HOWEVER, THE PROCESS OF INSOMNIA IN THIS POPULATION HAS been largely understudied. Knowledge of this process would not only aid in further understanding insomnia in the context of breast cancer, but it would also foster the development of insomnia interventions for this population so that this prevalent and distressing issue could be better managed. One model commonly used to understand the process of insomnia is a cognitive-behavioral model, which asserts that both dysfunctional sleep related thoughts (e.g., worries about the consequences of insomnia) and behaviors (e.g., napping, extending the opportunity to sleep, staying in bed awake) perpetuate insomnia long after precipitating factors may dissipate.7,8 A large body of research shows support for this model in the context of primary insomnia (i.e., insomnia without any comorbid condition)9,12–13 and demonstrates the efficacy and effectiveness of cognitive-behavioral therapy for insomnia (CBT) for primary insomnia.14 In addition, a few studies have shown support for aspects of this model in the context of insomnia comorbid with breast cancer3,15–19 as well as demonstrated the efficacy of CBT for this population.20–22 Although a cognitive-behavioral model of insomnia shows promise in understanding the process of insomnia in breast cancer patients, cancer-related factors that could potentially contribute to sleep difficulties must be considered. Breast cancer symptoms, such as pain, fatigue, hot flashes, and mood disturbance, are of particular interest as these symptoms have been shown to be associated with poorer sleep in this population.2,3,19,23–27 Therefore, the current study sought to examine the contribution of pain, fatigue, hot flashes, mood disturbance, dysfunctional sleep related thoughts, and sleep inhibitory behaviors to the process of insomnia in breast cancer patients. Process-related questions are challenging to answer with traditional statistical techniques, which typically treat data in a cross-sectional and aggregated fashion. Fortunately, there is a methodological approach, which has been used in other areas (e.g., pain and mood) to examine process-related questions.28,29 This approach is called a daily process approach, which includes repeated prospective measurement of variables that are considered to change in meaningful ways on a daily basis.30 Using sophisticated multilevel modeling techniques, this approach provides the unique opportunity to examine relationships as they occur over time.30–33 For example, one can examine whether higher levels of pain during the day are related to poorer sleep that night and/or if poorer sleep that night is related to higher levels of pain the next day. Therefore, using a daily process approach, the current study addressed three main questions in a population of breast cancer patients with insomnia. First, to examine nighttime associations, what is the day-to-day relationship between sleep and nighttime pain and hot flashes? Second, to examine the antecedents of poorer sleep, what is the day-to-day relationship between daytime symptoms, dysfunctional sleep related thoughts, and sleep inhibitory behaviors and that night's sleep? Third, to examine the consequences of poorer sleep, what is the day-to-day relationship between sleep and the next day's symptoms, dysfunctional sleep related thoughts, and sleep inhibitory behaviors?