OBJECTIVES: Existing research demonstrates that breast cancer survivors (BCS) report poor sleep as a side effect of estrogen deprivation therapy (EDT) (Berkowitz et al, 2021; Van Dyk et al, 2021; Martin et al, 2021). Despite their potential importance, validated & objective measures of sleep are not yet widely incorporated into breast cancer research.

This study aimed to employ actigraph technology to capture real time objective sleep data in a population of BCS on EDT. In addition, surveys captured patient demographics and self-reported sleep data to allow comparison between objective sleep quality and subjective patient reported outcomes in BCS.

METHODS: Twenty-two BCS (female) were provided a ReadiWatch^TM (a wrist-worn actigraph) to assess objective sleep quality. Electronic surveys were administered at baseline, after one month, and at the end of the second month (the study’s conclusion) to assess perceived sleep and insomnia problems using Insomnia Severity Index (ISI) & Pittsburgh Sleep Quality Index (PSQI). Participants were able to access their sleep data on their mobile device using the ReadiWatch^TM application after one month of ReadiWatch^TM wear. Type of EDT was recorded for each participant.

RESULTS: Four main types of pharmacotherapy were identified as EDT for the participants: anastrozole, exemestane, letrozole, and tamoxifen. Of those, the majority of participants were receiving either anastrozole (36%) or tamoxifen (32%). Participants receiving anastrozole and tamoxifen had significantly decreased self-reported sleep (higher ISI & PSQI scores) compared to those on alternate therapies. Additionally, actigraphy demonstrated that participants receiving tamoxifen and anastrozole had significantly lower objective sleep quality.

CONCLUSIONS: Data suggest that pharmacotherapy type may impact both the subjective and objective BCS experience of sleep during EDT. Thus, this study’s findings may help inform future clinical conversations surrounding sleep in BCS as well as strategies for mitigation of sleep disturbances in this population.