Assessment of sleep and circadian rhythms of endocrine and immune function among women With advanced breast cancer

Background Previous findings indicate important effects of stress, disrupted sleep, and dysregulated circadian rhythms on the progression of cancer. Our understanding of these relationships, however, has been limited by the absence of data from 24-h continuous physiologic monitoring of hormonal and immune activity with simultaneous collection of objective sleep data. The present study successfully employed such an intensive protocol among women with advanced breast cancer. Purpose In this paper we describe our protocol in detail. We provide methodological and practical suggestions for assessing sleep and circadian rhythms in the medically ill. Finally, we offer psychological and physical safety guidelines for future studies that aim to utilize similar protocols. Results We enrolled 123 women with advanced breast cancer; 18 dropped out, 105 participated (6 provided incomplete data, and 99 completed the protocol). The protocol included: (1) psychological/medical screenings and assessments; (2) a 2-week at-home sleep study, including wrist actigraphy and two nights of polysomnography (PSG); and (3) 28 h in-hospital collection of measures of hormones and immune function, in conjunction with one night of PSG for assessing sleep stages, respiration, and leg movement. Based on the implementation challenges we faced, protocol adjustments were made to address feasibility limitations and to accommodate participant preferences and medical/physiological needs. Conclusions By combining and modifying the gold standard protocols for sleep and circadian assessments, researchers can compassionately optimize participant enrollment and protocol compliance, and minimize attrition.