Wu Anna H, Wang Renwei, Koh Woon-Puay, Stanczyk Frank Z, Lee Hin-Peng, Yu Mimi C
Department of Preventive Medicine, University of Southern California Keck School of Medicine, 1441 Eastlake Avenue, Los Angeles, CA 90089, USA.
Carcinogenesis. 2008 Jun;29(6):1244-8. doi: 10.1093/carcin/bgn100. Epub 2008 Apr 30.
Sleep duration has been hypothesized to be inversely associated with breast cancer risk, possibly due to greater overall melatonin production in longer sleepers. However, data are inconclusive from the three studies conducted in Western populations on sleep duration and breast cancer risk.
We investigated the relationship between self-reported usual sleep duration determined at baseline and subsequent risk of breast cancer in the prospective, population-based cohort of the Singapore Chinese Health Study. We excluded from the study women with <2 years of follow-up due to possible change in sleep pattern among breast cancer cases close to the time of diagnosis. Five hundred and twenty-five incident cases of breast cancer were identified among the remaining 33 528 women after up to 11 years of follow-up.
Among women postmenopausal at baseline, breast cancer risk decreased with increasing sleep duration (P trend = 0.047); those who reported 9+ h of sleep showed a relative risk of 0.67 (95% confidence interval = 0.4-1.1) compared with women who reported < or =6 h of sleep. This inverse association was observed primarily in lean women [i.e. body mass index below the median value (23.2 kg/m(2))] (P = 0.024). In this study population, irrespective of gender, urinary 6-sulfatoxymelatonin levels increased with increasing self-reported hours of sleep (P trend = 0.035) after adjustment for age and time of day of urine collection. Melatonin levels were 42% higher in those with 9+ versus those with < or =6 h of sleep.
Sleep duration may influence breast cancer risk, possibly via its effect on melatonin levels.
有假设认为睡眠时间与乳腺癌风险呈负相关，这可能是因为睡眠时间较长者体内褪黑素的总体分泌量更高。然而，西方人群中关于睡眠时间与乳腺癌风险的三项研究所得数据尚无定论。
在以人群为基础的前瞻性队列研究“新加坡华人健康研究”中，我们调查了基线时自我报告的通常睡眠时间与后续患乳腺癌风险之间的关系。由于乳腺癌患者在临近诊断时睡眠模式可能发生变化，我们将随访时间不足2年的女性排除在研究之外。在长达11年的随访后，在其余33528名女性中确定了525例乳腺癌新发病例。
在基线时已绝经的女性中，乳腺癌风险随睡眠时间的增加而降低（P趋势 = 0.047）；与报告睡眠时长小于或等于6小时的女性相比，报告睡眠时长为9小时及以上的女性相对风险为0.67（95%置信区间 = 0.4 - 1.1）。这种负相关主要在瘦女性[即体重指数低于中位数（23.2 kg/m²）]中观察到（P = 0.024）。在本研究人群中，无论性别，在调整年龄和尿液采集时间后，尿中6 - 硫酸氧褪黑素水平随自我报告的睡眠时间增加而升高（P趋势 = 0.035）。睡眠时长为9小时及以上者的褪黑素水平比睡眠时长小于或等于6小时者高42%。
睡眠时间可能会影响乳腺癌风险，可能是通过其对褪黑素水平的影响来实现的。
