Sletten Tracey L, Ftouni Suzanne, Nicholas Christian L, Magee Michelle, Grunstein Ronald R, Ferguson Sally, Kennaway David J, O'Brien Darren, Lockley Steven W, Rajaratnam Shantha M W
Monash Institute of Cognitive and Clinical Neurosciences and School of Psychological Sciences, Monash University, Melbourne, Victoria, Australia.
CRC for Alertness, Safety and Productivity, Clayton, Victoria, Australia.
Occup Environ Med. 2017 Nov;74(11):792-801. doi: 10.1136/oemed-2016-103818. Epub 2017 Jun 19.
Night workers often experience high levels of sleepiness due to misalignment of the sleep-wake cycle from the circadian pacemaker, in addition to acute and chronic sleep loss. Exposure to light, in particular short wavelength light, can improve alertness and neurobehavioural performance. This randomised controlled trial examined the efficacy of blue-enriched polychromatic light to improve alertness and neurobehavioural performance in night workers.
Participants were 71 night shift workers (42 males; 32.8±10.5 years) who worked at least 6 hours between 22:00 and 08:00 hours. Sleep-wake logs and wrist actigraphy were collected for 1-3 weeks, followed by 48-hour urine collection to measure the circadian 6-sulphatoxymelatonin (aMT6s) rhythm. On the night following at least two consecutive night shifts, workers attended a simulated night shift in the laboratory which included subjective and objective assessments of sleepiness and performance. Workers were randomly assigned for exposure to one of two treatment conditions from 23:00 hours to 07:00 hours: blue-enriched white light (17 000 K, 89 lux; n=36) or standard white light (4000 K, 84 lux; n=35).
Subjective and objective sleepiness increased during the night shift in both light conditions (p<0.05, η=0.06-0.31), but no significant effects of light condition were observed. The 17 000 K light, however, did improve subjective sleepiness relative to the 4000 K condition when light exposure coincided with the time of the aMT6s peak (p<0.05, d=0.41-0.60).
This study suggests that, while blue-enriched light has potential to improve subjective sleepiness in night shift workers, further research is needed in the selection of light properties to maximise the benefits.
The Australian New Zealand Clinical Trials Registry ACTRN12610000097044 (https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=320845&isReview=true).
夜班工作者除了急性和慢性睡眠不足外，还常常因睡眠 - 觉醒周期与昼夜节律起搏器失调而感到极度困倦。暴露于光线下，尤其是短波长光，可以提高警觉性和神经行为表现。这项随机对照试验研究了富含蓝光的多色光改善夜班工作者警觉性和神经行为表现的效果。
参与者为71名夜班工作者（42名男性；年龄32.8±10.5岁），他们在22:00至08:00之间至少工作6小时。收集1 - 3周的睡眠 - 觉醒日志和手腕活动记录，随后进行48小时尿液收集以测量昼夜节律的6 - 硫酸氧褪黑素（aMT6s）节律。在至少连续两个夜班后的晚上，参与者在实验室参加模拟夜班，其中包括对困倦程度和表现的主观和客观评估。参与者被随机分配在23:00至07:00之间暴露于两种治疗条件之一：富含蓝光的白光（17000K，89勒克斯；n = 36）或标准白光（4000K，84勒克斯；n = 35）。
在两种光照条件下，夜班期间主观和客观困倦程度均增加（p < 0.05，η = 0.06 - 0.31），但未观察到光照条件的显著影响。然而，当光照时间与aMT6s峰值时间一致时，相对于4000K条件，17000K的光确实改善了主观困倦程度（p < 0.05，d = 0.41 - 0.60）。
本研究表明，虽然富含蓝光的光有潜力改善夜班工作者的主观困倦程度，但在选择光的特性以最大化益处方面还需要进一步研究。
澳大利亚新西兰临床试验注册中心ACTRN12610000097044（https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=320845&isReview=true）。
