Sleep Clinic Chofu, Tokyo, Japan.
Department of Psychiatry, University of California, San Diego, CA, USA.
Psychiatry Investig. 2015 Apr;12(2):177-82. doi: 10.4306/pi.2015.12.2.177. Epub 2014 Dec 12.
Concern that disturbances of sleep and light exposures at night might increase cancer risks have been expressed, but little actual exposure data has been collected. Measurements from a representative population sample were examined to understand the magnitude of in-bed light exposure at night and possible correlates.
From 1990 to 1994, a home survey of sleep disorders among adults ages 40-64 was conducted in the City of San Diego California, using stratified representative sampling techniques. Along with questionnaires, sleep logs, and 3-night wrist activity and pulse oximetry measures, bedside illumination was measured with a computer recording system. Questionnaires included the CESD depression scale and a scale of symptoms typical of winter depression.
Complete data were available from 286 men and women, whose mean in-bed intervals averaged 7 hours and 42 minutes. The mean room illumination during the first part of the night was mean 12.7 lux (median 3.2 lux) and during the last 2 hours in bed averaged 28.7 lux (median 18.9 lux). Nocturnal light exposure was positively correlated with age, male gender, summer season, time in bed, wake-up time, and depressive symptoms.
Complex bi-directional interactions may take place between sleep disturbances, depression, time in bed, wake-up-time, and in-bed illumination. The most crucial light exposures appear to occur in the last 2 hours in bed, largely after dawn, so daylight exposure may be an important factor.
人们担心睡眠紊乱和夜间光照暴露可能会增加癌症风险，但实际上很少收集到相关的暴露数据。本研究通过对代表性人群样本进行测量，以了解夜间卧床时的光照暴露程度及其可能的相关因素。
1990 年至 1994 年，在加利福尼亚州圣地亚哥市对 40-64 岁成年人的睡眠障碍进行了一项家庭调查，采用分层代表性抽样技术。除了问卷调查、睡眠日志和 3 晚腕部活动和脉搏血氧仪测量外，还使用计算机记录系统测量床边照明。问卷包括 CESD 抑郁量表和冬季抑郁典型症状量表。
共有 286 名男性和女性提供了完整的数据，他们的平均卧床时间为 7 小时 42 分钟。夜间前半段的平均房间照度为 12.7 勒克斯（中位数 3.2 勒克斯），后半段平均为 28.7 勒克斯（中位数 18.9 勒克斯）。夜间光照暴露与年龄、男性性别、夏季、卧床时间、起床时间和抑郁症状呈正相关。
睡眠障碍、抑郁、卧床时间、起床时间和卧床光照之间可能存在复杂的双向相互作用。最关键的光照暴露似乎发生在卧床的最后 2 小时内，主要是在黎明之后，因此日光暴露可能是一个重要因素。
