Circadian rhythms, symptoms, physical functioning, and body mass index in breast cancer survivors

Introduction: Research has been limited in circadian activity rhythms and their relationship with health status in early-stage breast cancer survivors. Maintaining strong circadian parameters may reduce symptoms and improve physical functioning and disease-free survival. Methods: This is a descriptive, correlational, secondary analysis of data from a randomized controlled trial collected 1 year after the first chemotherapy treatment; n = 156 cases with 7 days of wrist actigraph data of six circadian activity rhythm parameters; measures of function, fatigue, sleep, and anxiety/depression; and demographic/medical data including body mass index (BMI). Results: In the total sample and three BMI categories, acrophase was the only circadian parameter that reached means established in healthy adults. In the total sample, phase-delayed acrophase was associated with higher depression (r = 0. 180, p = 0. 025) and lower morning energy (r = -0. 194, p = 0. 016) and trended for higher fatigue (r = 0. 153, p = 0. 057). Lower morning energy was also associated with a lower circadian quotient (r = 0. 158, p = 0. 05). As BMI increased, weaker circadian parameters were recorded consistently. When compared with women in normal BMI categories, obese women's amplitude and 24-h autocorrelation coefficient were significantly weaker (p = 0. 011-0. 015). In obese women, phase-delayed acrophase was correlated with higher fatigue and anxiety and with lower morning energy and physical functioning. Discussion/conclusions: Amplitude and 24-h autocorrelation parameters were significantly weaker, and phase-delayed acrophase was linked to several more intense symptoms and lower physical functioning in obese women. Implications for cancer survivors: Clinicians need to target high-risk women with phase-delayed rhythms, higher symptoms, and lower physical functioning for intervention.