Department of Indoor Environmental Medicine, Nara Medical University School of Medicine, 840 Shijocho, Kashiharashi, Nara 634-8521, Japan.
J Clin Endocrinol Metab. 2012 Nov;97(11):4166-73. doi: 10.1210/jc.2012-1873. Epub 2012 Sep 4.
Melatonin is involved in a variety of diseases, including cancer, insomnia, depression, dementia, hypertension, and diabetes; its secretion is influenced by environmental light. Although daylight exposure increases nocturnal melatonin secretion in a controlled laboratory setting, whether it increases nocturnal melatonin secretion in an uncontrolled daily life setting remains unclear.
We aimed to determine the association between daylight exposure in an uncontrolled daily life setting and urinary 6-sulfatoxymelatonin excretion.
A cross-sectional study was conducted in 192 elderly individuals (mean age, 69.9 yr).
We measured ambulatory daylight exposure using a wrist light meter in two 48-h sessions; furthermore, we measured overnight urinary 6-sulfatoxymelatonin excretion, an index of melatonin secretion, on the second night of each session.
The median duration of daylight exposure of at least 1000 lux was 72 min (interquartile range, 37-124). Univariate linear regression analysis showed marginal to significant associations between log-transformed urinary 6-sulfatoxymelatonin excretion and age, current smoking status, benzodiazepine use, day length, log-transformed duration of daylight exposure of at least 1000 lux, and daytime physical activity. In a multivariate model, log-transformed duration of daylight exposure of at least 1000 lux was significantly associated with log-transformed urinary 6-sulfatoxymelatonin excretion (regression coefficient, 0.101; 95% confidence interval, 0.003-0.199; P = 0.043). Furthermore, an increase in the duration of daylight exposure of at least 1000 lux from 37 to 124 min (25th to 75th percentiles) was associated with a 13.0% increase in urinary 6-sulfatoxymelatonin excretion (6.8 to 7.7 μg).
Daylight exposure in an uncontrolled daily life setting is positively associated with urinary 6-sulfatoxymelatonin excretion in the elderly.
褪黑素参与多种疾病，包括癌症、失眠、抑郁、痴呆、高血压和糖尿病；其分泌受环境光的影响。尽管在受控的实验室环境中，日光照射会增加夜间褪黑素的分泌，但在不受控制的日常生活环境中是否会增加夜间褪黑素的分泌尚不清楚。
我们旨在确定日常生活环境中日光照射与尿液 6-硫酸褪黑素排泄量之间的关联。
这是一项横断面研究，共纳入 192 名老年人（平均年龄 69.9 岁）。
我们使用腕式光计在两个 48 小时的时间段内测量日间光照暴露量；此外，我们在每个时间段的第二天晚上测量夜间尿液 6-硫酸褪黑素排泄量，这是褪黑素分泌的指标。
至少 1000 勒克斯的日光暴露时间中位数为 72 分钟（四分位间距 37-124）。单变量线性回归分析显示，尿液 6-硫酸褪黑素排泄量的对数值与年龄、当前吸烟状况、苯二氮䓬类药物使用、昼长、至少 1000 勒克斯的日光暴露时间的对数值以及白天体力活动呈边缘到显著相关。在多变量模型中，至少 1000 勒克斯的日光暴露时间的对数值与尿液 6-硫酸褪黑素排泄量的对数值显著相关（回归系数 0.101；95%置信区间 0.003-0.199；P=0.043）。此外，至少 1000 勒克斯的日光暴露时间从 37 分钟增加到 124 分钟（25 至 75 百分位数）与尿液 6-硫酸褪黑素排泄量增加 13.0%相关（6.8 至 7.7μg）。
日常生活环境中的日光暴露与老年人尿液 6-硫酸褪黑素排泄量呈正相关。
