Associations between morning–evening chronotype, fatigue, and QOL in breast cancer survivors.

Abstract

246 Background: Emerging evidence suggests that circadian disruption is associated with cancer and cancer treatments. Chronotype is defined as a behaviorally manifested preference for a certain timing of sleep and activity. Previous studies have revealed that living out of sync from one’s innate chronotype can have detrimental effects on one’s health. Although there has been research examining the associations between chronotype and health, not much is known about the relationship between chronotype, fatigue, and QOL in cancer survivors. Methods: 68 Breast cancer survivors completed questionnaires to assess their chronotype (Horne-Ostberg), to rate their fatigue (MDASI), and to evaluate their QOL (FACIT). The Horne-Ostberg questionnaire yields a range of values indicating survivors’ preference for early or late activity. The study sample was divided by terciles according to survivors’ “morningness” or “eveningness” preferences (i.e., chronotypes). Results: Morning chronotype was associated with significantly less severe tiredness and drowsiness as well as significantly better physical well-being and fatigue subscale scores as compared to evening chronotype. Tiredness median (M) scores were highest for evening chronotype (M=5.5), moderate for mid-range chronotype (M=4.5), and lowest for morning chronotype (M=3.0), a significant difference (p=0.046). Drowsiness scores were highest for evening chronotype (median=6.0), moderate for mid-range chronotype (M=4.0), and lowest for morning chronotype (M=3.0), p=0.046. The median score for physical well-being was significantly lower for evening compared to morning chronotypes (22.5 vs. 25.0, p=0.038) and morning types reported significantly better health in respect to fatigue compared to evening types (40.5 vs. 35.5, p=0.045). Conclusions: Survivors with early chronotype (early to bed, early to rise) reported less fatigue, drowsiness, and better overall physical well-being. While chronotype is believed to be genetically driven, certain behavioral, pharmacological, and bright light modifications can be used to help patients shift their circadian rhythm towards earlier morning type and may experience improvements in physical well-being.