Obayashi Kenji, Saeki Keigo, Iwamoto Junko, Okamoto Nozomi, Tomioka Kimiko, Nezu Satoko, Ikada Yoshito, Kurumatani Norio
Department of Community Health and Epidemiology and.
Chronobiol Int. 2014 May;31(4):461-7. doi: 10.3109/07420528.2013.840647. Epub 2013 Oct 22.
Epidemiologic data have demonstrated associations of sleep-onset insomnia with a variety of diseases, including depression, dementia, diabetes and cardiovascular diseases. Sleep initiation is controlled by the suprachiasmatic nucleus of the hypothalamus and endogenous melatonin, both of which are influenced by environmental light. Exposure to evening light is hypothesized to cause circadian phase delay and melatonin suppression before bedtime, resulting in circadian misalignment and sleep-onset insomnia; however, whether exposure to evening light disturbs sleep initiation in home settings remains unclear. In this longitudinal analysis of 192 elderly individuals (mean age: 69.9 years), we measured evening light exposure and sleep-onset latency for 4 days using a wrist actigraph incorporating a light meter and an accelerometer. Mixed-effect linear regression analysis for repeated measurements was used to evaluate the effect of evening light exposure on subsequent sleep-onset latency. The median intensity of evening light exposure and the median sleep-onset latency were 27.3 lux (interquartile range, 17.9-43.4) and 17 min (interquartile range, 7-33), respectively. Univariate models showed significant associations between sleep-onset latency and age, gender, daytime physical activity, in-bed time, day length and average intensity of evening and nighttime light exposures. In a multivariate model, log-transformed average intensity of evening light exposure was significantly associated with log-transformed sleep-onset latency independent of the former potential confounding factors (regression coefficient, 0.133; 95% CI, 0.020-0.247; p = 0.021). Day length and nighttime light exposure were also significantly associated with log-transformed sleep-onset latency (p = 0.001 and p < 0.001, respectively). In conclusion, exposure to evening light in home setting prolongs subsequent sleep-onset latency in the elderly.
流行病学数据已证明入睡失眠与多种疾病有关，包括抑郁症、痴呆症、糖尿病和心血管疾病。睡眠起始由下丘脑的视交叉上核和内源性褪黑素控制，这两者均受环境光的影响。据推测，睡前接触傍晚光线会导致昼夜节律相位延迟和褪黑素抑制，从而导致昼夜节律失调和入睡失眠；然而，在家庭环境中接触傍晚光线是否会干扰睡眠起始仍不清楚。在这项对192名老年人（平均年龄：69.9岁）的纵向分析中，我们使用结合了光度计和加速度计的腕部活动记录仪测量了4天的傍晚光线暴露和入睡潜伏期。采用重复测量的混合效应线性回归分析来评估傍晚光线暴露对随后入睡潜伏期的影响。傍晚光线暴露的中位数强度和入睡潜伏期的中位数分别为27.3勒克斯（四分位间距，17.9 - 43.4）和17分钟（四分位间距，7 - 33）。单变量模型显示入睡潜伏期与年龄、性别、白天身体活动、卧床时间、日长以及傍晚和夜间光线暴露的平均强度之间存在显著关联。在多变量模型中，经对数转换的傍晚光线暴露平均强度与经对数转换的入睡潜伏期显著相关，且不受先前潜在混杂因素的影响（回归系数，0.133；95%置信区间，0.020 - 0.247；p = 0.021）。日长和夜间光线暴露也与经对数转换的入睡潜伏期显著相关（分别为p = 0.001和p < 0.001）。总之，在家庭环境中接触傍晚光线会延长老年人随后的入睡潜伏期。
