Yang W, et al. - Using a community-based 1 : 1 individual matched case–control design, researchers assessed the risk of breast cancer (BC) incidence in relation to a broad range of sleep domains among female patients with incident BC (n=401) and 401 age-matched and area-matched female controls (n=401) in Jiujiang, China. An increased risk of BC was reported in relation to light exposure at night (highest vs lowest level), habitual timing of sleep (after 12 a.m. midnight vs before 22 p.m.), night/shift work (yes vs no), and frequency of night-time wakings (>2 per night vs never), after mutually adjusting for other sleep parameters. Regardless of menopausal status and tumor estrogen receptor status, the persistence of these positive links was reported. In this study, no link was found between sleep duration, sleep quality, sleep medication use, insomnia frequency, daytime nap, and the risk of BC.