Sleep and circadian disruption and incident breast cancer risk: An evidence-based and theoretical review

Abstract

Opportunities for restorative sleep and optimal sleep-wake schedules are becoming luxuries in industrialized cultures, yet accumulating research has revealed multiple adverse health effects of disruptions in sleep and circadian rhythms, including increased risk of breast cancer. The literature on breast cancer risk has focused largely on adverse effects of night shift work and exposure to light at night (LAN), without considering potential effects of associated sleep disruptions. As it stands, studies on breast cancer risk have not considered the impact of both sleep and circadian disruption, and the possible interaction of the two through bidirectional pathways, on breast cancer risk in the population at large. We review and synthesize this literature, including: 1) studies of circadian disruption and incident breast cancer; 2) evidence for bidirectional interactions between sleep and circadian systems; 3) studies of sleep and incident breast cancer; and 4) potential mechanistic pathways by which interrelated sleep and circadian disruption may contribute to the etiology of breast cancer.

Associations of bedtime, sleep duration, and sleep quality with semen quality in males seeking fertility treatment: a preliminary study

“…Mots-clés: Sommeil, Heure du Coucher, Durée du Sommeil, Qualité du Sommeil, Qualité du Sperme, Fertilité masculine Background A growing number of studies indicate an association between poor sleep and negative health outcomes. These include increased risk of cardio-metabolic complications, hypertension, obesity, type 2-diabetes, cardiovascular disease, urologic complications, cancer, and depression [1][2][3][4][5][6]. Results from a limited number of recent studies suggest that inadequate bedtimes, short sleep duration, and poor sleep, assessed as poor self-reported sleep quality, may impact semen quality [7][8][9][10][11][12][13].…”

Investigating causal relationships between sleep traits and risk of breast cancer: a Mendelian randomization study

“…However, the biological role of many of the genetic variants used to instrument these traits in Mendelian randomization and mechanistic pathways underlying the observed effects are not well understood. Previously reported pathways between sleep disruption and mammary oncogenesis include immunological, molecular, cellular, neuroendocrine and metabolic processes (5). Further work to uncover these possible mediating processes is required.…”

“…However, much of the evidence for the carcinogenic effect of shift work comes from animal models rather than epidemiological or experimental studies in humans (1, 4). Furthermore, while the literature on breast cancer risk has focused on the potentially adverse effects of night shift work and exposure to light-at-night, there has been much less investigation into the potential adverse effects of sleep disruption and traits such as chronotype (morning/evening preference), sleep duration and insomnia (5).…”

Chronic circadian disruption modulates breast cancer cell stemness and their immune microenvironment to drive metastasis in mice

“…4 Since then, additional and better-documented epidemiologic studies, genome-wide association studies (GWAS) and cellular and animal studies confirmed the link between BCs development and circadian disruption. 5 A recent population-based case-control study confirms that factors including night work duration, length of shifts and time since last night shift affect the odd ratios for BC mostly in premenopausal women. 6 The hormonal receptor status is also important and BC risk associated with night work is only higher for ER+ HER2+ cancer.…”