Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA, USA.
Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA.
J Biol Rhythms. 2019 Feb;34(1):98-104. doi: 10.1177/0748730418818655. Epub 2018 Dec 17.
Age-related disrupted sleep has been associated with modifications in the timing of endogenous circadian rhythms. There are studies suggesting a decreased sensitivity of the aging circadian pacemaker to light. In this study, we aimed to test whether a moderate illuminance light stimulus would produce significant phase shifts in older adults, and whether those would fall in a range consistent with the illuminance response curve (IRC) we previously reported in older adults. We conducted an 8-day in-patient study with 12 healthy older participants (mean age [SD], 58.3 [4.2] y, 5 females). A 6.5-h polychromatic white light exposure with a target illuminance of 270 lux was administered beginning in the early biological night. Before and after the light exposure, a circadian phase estimation procedure was carried out, with plasma melatonin data used as a circadian phase marker. The mean phase delay produced by the light stimulus was 1.78 ± 0.77 h. Ten of the 12 phase delay shifts at ~270 lux fell within the 95% predictive interval of the model fit to data from our previous IRC in older adults. This finding demonstrates that the circadian system of healthy older adults is sensitive to the phase-delaying effects of a moderate intensity light stimulus. The magnitude of the observed phase shifts is consistent with the previously described IRC in older adults.
与内源性昼夜节律定时变化相关的与年龄相关的睡眠障碍，已有研究表明衰老生物钟对光的敏感性降低。在这项研究中，我们旨在测试适度照度的光刺激是否会导致老年人出现明显的相位延迟，以及这些相位延迟是否落在我们之前在老年人中报告的照度反应曲线（IRC）范围内。我们进行了一项为期 8 天的住院研究，共有 12 名健康的老年人参与者（平均年龄[标准差]，58.3[4.2]岁，女性 5 名）。从早期生物夜间开始，给予目标照度为 270 勒克斯的 6.5 小时多色白光暴露。在光暴露之前和之后，进行了昼夜相位估计程序，使用血浆褪黑素数据作为昼夜相位标记。光刺激产生的平均相位延迟为 1.78±0.77 小时。在 270 勒克斯左右的 12 个相位延迟变化中，有 10 个落在我们之前在老年人中 IRC 拟合数据的 95%预测区间内。这一发现表明，健康老年人的昼夜节律系统对适度强度光刺激的相位延迟效应敏感。观察到的相位延迟幅度与之前在老年人中描述的 IRC 一致。
