Phipps-Nelson Jo, Redman Jennifer R, Schlangen Luc J M, Rajaratnam Shantha M W
School of Psychology, Psychiatry and Psychological Medicine, Monash University, Clayton, Victoria, Australia.
Chronobiol Int. 2009 Jul;26(5):891-912. doi: 10.1080/07420520903044364.
This study examined the effects of nocturnal exposure to dim, narrowband blue light (460 nm, approximately 1 lux, 2 microW/cm2), compared to dim broad spectrum (white) ambient light ( approximately 0.2 lux, 0.5 microW/cm2), on subjective and objective indices of sleepiness during prolonged nighttime performance testing. Participants were also exposed to a red light (640 nm, approximately 1 lux, 0.7 microW/cm2) placebo condition. Outcome measures were driving simulator and psychomotor vigilance task (PVT) performance, subjective sleepiness, salivary melatonin, and electroencephalographic (EEG) activity. The study had a repeated-measures design, with three counterbalanced light conditions and a four-week washout period between each condition. Participants (n = 8) maintained a regular sleep-wake schedule for 14 days prior to the approximately 14 h laboratory study, which consisted of habituation to light conditions followed by neurobehavioral performance testing from 21:00 to 08:30 h under modified constant-routine conditions. A neurobehavioral test battery (2.5 h) was presented four times between 21:00 and 08:30 h, with a 30 min break between each. From 23:30 to 05:30 h, participants were exposed to blue or red light, or remained in ambient conditions. Compared to ambient light exposure, blue light exposure suppressed EEG slow wave delta (1.0-4.5 Hz) and theta (4.5-8 Hz) activity and reduced the incidence of slow eye movements. PVT reaction times were significantly faster in the blue light condition, but driving simulator measures, subjective sleepiness, and salivary melatonin levels were not significantly affected by blue light. Red light exposure, as compared to ambient light exposure, reduced the incidence of slow eye movements. The results demonstrate that low-intensity, blue light exposure can promote alertness, as measured by some of the objective indices used in this study, during prolonged nighttime performance testing. Low intensity, blue light exposure has the potential to be applied to situations where it is desirable to increase alertness but not practical or appropriate to use bright light, such as certain occupational settings.
本研究考察了夜间暴露于昏暗的窄带蓝光（460纳米，约1勒克斯，2微瓦/平方厘米）与昏暗的广谱（白色）环境光（约0.2勒克斯，0.5微瓦/平方厘米）相比，在长时间夜间性能测试期间对嗜睡主观和客观指标的影响。参与者还暴露于红光（640纳米，约1勒克斯，0.7微瓦/平方厘米）安慰剂条件下。结果指标包括驾驶模拟器和心理运动警觉任务（PVT）表现、主观嗜睡、唾液褪黑素以及脑电图（EEG）活动。该研究采用重复测量设计，有三种平衡的光照条件，且每种条件之间有四周的洗脱期。参与者（n = 8）在约14小时的实验室研究前保持规律的睡眠-觉醒时间表14天，该研究包括适应光照条件，随后在改良的恒定日常条件下从21:00至08:30进行神经行为性能测试。在21:00至08:30之间，神经行为测试组（2.5小时）进行了四次，每次之间有30分钟的休息时间。从23:30至05:30，参与者暴露于蓝光或红光下，或保持在环境光条件下。与暴露于环境光相比，蓝光暴露抑制了脑电图慢波δ（1.0 - 4.5赫兹）和θ（4.5 - 8赫兹）活动，并降低了慢眼动的发生率。在蓝光条件下，PVT反应时间显著更快，但驾驶模拟器测量结果、主观嗜睡和唾液褪黑素水平未受到蓝光的显著影响。与暴露于环境光相比，红光暴露降低了慢眼动的发生率。结果表明，在长时间夜间性能测试期间，如本研究中使用的一些客观指标所测量的，低强度蓝光暴露可促进警觉性。低强度蓝光暴露有可能应用于需要提高警觉性但使用强光不实际或不合适的情况，如某些职业环境。
