Melatonin suppression during a simulated night shift in medium intensity light is increased by 10-minute breaks in dim light and decreased by 10-minute breaks in bright light
Melatonin suppression during a simulated night shift in medium intensity light is increased by 10-minute breaks in dim light and decreased by 10-minute breaks in bright light
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DOI：
10.1080/07420528.2020.1752704
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发表时间：
2020-04-25
影响因子：
2.8
通讯作者：
Higuchi, Shigekazu
中科院分区：
文献类型：
--
作者：
Lee, Sang-Il;Kinoshita, Saki;Higuchi, Shigekazu
夜间暴露在光线下会破坏内源性昼夜节律和/或抑制松果体褪黑激素，从而导致急性或慢性不良健康问题。在本研究中，我们调查了短时间暴露在非常昏暗的光线或非常明亮的光线下是否会影响褪黑激素抑制、主观嗜睡和暴露在恒定的中等明亮光线下的表现。24名健康男大学生被分为两个实验组，其中一半（平均年龄：20.0±0.9岁）分别参加中强光（430 lx，中间断）和极弱光（< 1 lx，弱间断）的短时间（10分钟）光照条件下的实验，另一半(平均年龄：21.3 +/- 2.5岁)参加了中强光（430 lx，中等间断）和强光（4700 lx，明亮间断）短时间光照条件的实验。每个模拟夜班由5组组成（每组50分钟夜班和10分钟休息时间），时间为01:00 - 06:00。受试者在夜间工作期间暴露在中等强度光（550 lx）下。从02:00至06:00每小时进行一次10分钟的休息。测量唾液褪黑素浓度，评估主观嗜睡，从21:00至实验结束每小时进行一次精神运动警戒任务。与中等休息条件下04:00 - 06:00 h的褪黑素抑制相比，昏暗休息条件显著促进褪黑素抑制，明亮休息条件显著降低褪黑素抑制。然而，无论是昏暗的休息还是明亮的休息，对主观嗜睡和精神运动警觉性任务的表现都没有显著的影响。我们的研究结果表明，在暴露于恒定光环境期间，短时间的周期性暴露会影响松果体褪黑素对恒定光的敏感性，这取决于两种光条件下光强度的差异（即短光暴露与恒定光暴露）。此外，我们的研究结果表明，夜间暴露在不同强度的光线下可能是影响夜间工作环境中光诱导的褪黑激素抑制的一个因素。
Exposure to light at night results in disruption of endogenous circadian rhythmicity and/or suppression of pineal melatonin, which can consequently lead to acute or chronic adverse health problems. In the present study, we investigated whether exposure to very dim light or very bright light for a short duration influences melatonin suppression, subjective sleepiness, and performance during exposure to constant moderately bright light. Twenty-four healthy male university students were divided into two experimental groups: Half of them (mean age: 20.0 +/- 0.9 years) participated in an experiment for short-duration (10 min) light conditions of medium intensity light (430 lx, medium breaks) vs. very dim light (< 1 lx, dim breaks) and the other half (mean age: 21.3 +/- 2.5 years) participated in an experiment for short-duration light conditions of medium intensity light (430 lx, medium breaks) vs. very bright light (4700 lx, bright breaks). Each simulated night shift consisting of 5 sets (each including 50-minute night work and 10-minute break) was performed from 01:00 to 06:00 h. The subjects were exposed to medium intensity light (550 lx) during the night work. Each 10-minute break was conducted every hour from 02:00 to 06:00 h. Salivary melatonin concentrations were measured, subjective sleepiness was assessed, the psychomotor vigilance task was performed at hourly intervals from 21:00 h until the end of the experiment. Compared to melatonin suppression between 04:00 and 06:00 h in the condition of medium breaks, the condition of dim breaks significantly promoted melatonin suppression and the condition of bright breaks significantly diminished melatonin suppression. However, there was no remarkable effect of either dim breaks or bright breaks on subjective sleepiness and performance of the psychomotor vigilance task. Our findings suggest that periodic exposure to light for short durations during exposure to a constant light environment affects the sensitivity of pineal melatonin to constant light depending on the difference between light intensities in the two light conditions (i.e., short light exposure vs. constant light exposure). Also, our findings indicate that exposure to light of various intensities at night could be a factor influencing the light-induced melatonin suppression in real night work settings.