Department of Psychology, University of Pittsburgh, Pittsburgh, PA, USA.
Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Sleep. 2024 Jun 13;47(6). doi: 10.1093/sleep/zsae066.
Altered light sensitivity may be an underlying vulnerability for disrupted circadian photoentrainment. The photic information necessary for circadian photoentrainment is sent to the circadian clock from melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). The current study tested whether the responsivity of ipRGCs measured using the post-illumination pupil response (PIPR) was associated with circadian phase, sleep timing, and circadian alignment, and if these relationships varied by season or depression severity.
Adult participants (N = 323, agem = 40.5, agesd = 13.5) with varying depression severity were recruited during the summer (n = 154) and winter (n = 169) months. Light sensitivity was measured using the PIPR. Circadian phase was assessed using Dim Light Melatonin Onset (DLMO) on Friday evenings. Midsleep was measured using actigraphy. Circadian alignment was calculated as the DLMO-midsleep phase angle. Multilevel regression models covaried for age, gender, and time since wake of PIPR assessment.
Greater light sensitivity was associated with later circadian phase in summer but not in winter (β = 0.23; p = 0.03). Greater light sensitivity was associated with shorter DLMO-midsleep phase angles (β = 0.20; p = 0.03) in minimal depression but not in moderate depression (SIGHSAD < 6.6; Johnson-Neyman region of significance).
Light sensitivity measured by the PIPR was associated with circadian phase during the summer but not in winter, suggesting ipRGC functioning in humans may affect circadian entrainment when external zeitgebers are robust. Light sensitivity was associated with circadian alignment only in participants with minimal depression, suggesting circadian photoentrainment, a possible driver of mood, may be decreased in depression year-round, similar to decreased photoentrainment in winter.
光敏感性的改变可能是扰乱昼夜节律光适应的潜在弱点。昼夜节律光适应所需的光信息由含有黑视素的光感受器神经节细胞（ipRGC）发送到生物钟。本研究测试了使用光照后瞳孔反应（PIPR）测量的 ipRGC 反应性是否与昼夜节律相位、睡眠时间和昼夜节律对准有关，以及这些关系是否因季节或抑郁严重程度而异。
在夏季（n=154）和冬季（n=169）期间招募了患有不同抑郁严重程度的成年参与者（N=323，年龄均数=40.5，年龄标准差=13.5）。使用 PIPR 测量光敏感性。使用暗光褪黑素起始（DLMO）评估昼夜节律相位。使用活动记录仪测量中值睡眠。计算 DLMO-中值睡眠相位角作为昼夜节律对准。多水平回归模型协方差年龄、性别和 PIPR 评估后醒来时间。
夏季光敏感性与昼夜节律相位较晚相关，但冬季不相关（β=0.23；p=0.03）。夏季光敏感性与 DLMO-中值睡眠相位角较短相关（β=0.20；p=0.03），但在中度抑郁中不相关（SIGHSAD<6.6；Johnson-Neyman 显著性区域）。
使用 PIPR 测量的光敏感性与夏季的昼夜节律相位相关，但冬季不相关，表明人类 ipRGC 功能可能在外部 Zeitgebers 较强时影响昼夜节律适应。光敏感性仅与轻度抑郁患者的昼夜节律对准相关，表明昼夜节律光适应，一种可能驱动情绪的因素，可能全年都会在抑郁中下降，类似于冬季的光适应下降。
