黎明模拟光照对晨起睡眠惰性的影响

本研究考察了清晨唤醒后个体在睡眠惰性下的主观情绪、警觉性和认知加工的表现,以及利用动态黎明模拟光照能否对睡眠惰性产生有效的对抗作用。结果显示:(1)被试的积极情绪、主观警觉性在刚唤醒时显著低于基线水平,之后随时间推移逐渐提升。(2)被试醒后立即进行测试的认知加工成绩最差,随后逐渐提高,且主要表现在加工速度的回升上。(3)黎明模拟光照对醒后积极情绪、主观警觉性、持续性注意和抑制功能的恢复产生了明显的促进作用。这表明在睡眠惰性状态下个体的主客观活动会出现明显下降,而黎明模拟光照可在一定程度上对抗睡眠惰性带来的负性影响。

The Effect of Dawn Simulation on Morning Sleep Inertia

Sleep inertia is a process from sleep to fully wakeup.The transition entails a temporary period of confusion,disorientation,reduced alertness,bad affect and poor task performance.Previous studies have focused more on the pharmacological ways(e.g.,caffeine,excitant)of counteracting sleep inertia.However,there is little study investigating the non-pharmacological ways such as light exposure on the impact of sleep inertia post awakening up to now.The aim of the current study was to use behavior and PSG technique to explore the effect of morning sleep inertia on subjective alertness and mood as well as cognitive performance in healthy adults.We also examined whether exposure to dynamic dawn-simulated light could be a valid countermeasure against the detrimental effects of sleep inertia after waking up in the morning.A single factor within-subject design with lighting condition(at eye level)as independent variable was used in the present study.Three different light settings(separated by 1wk)were administered each morning after one 6-h sleep restriction night:A dawn-simulating light(starting 30min before scheduled wake-up time,polychromatic light gradually increasing from 0 to 210lux),a constant light(40lux for 30min before scheduled wake-up time)and a control condition(no light exposure prior to wake up).21 college students(9 males)participated in the study based on strict selection criteria.Sleep inertia was measured by a 2-h test protocol since wakeup,including subjective ratings of alertness,mood,and performance on a psychomotor vigilance task(PVT),a 2-back and a go/no-go task.Results were as follows:A paired t-test between baseline and the first post-sleep assessment revealed a significant difference in both KSS and PANAS scores such that subjective alertness and positive mood immediately after awakening were much lower than at baseline,thereafter declined over a 2-h period as indicated by a significant effect of time.Performance on PVT,2-back and go/no-go tasks were found to be significantly worse at the first test after wakeup than at baseline,and the effect of sleep inertia on these tasks dissipated over the course of two hours as indicated by a significant effect of time in the analysis of variance.Moreover,performance speed was more impaired than accuracy.Compared with control and constant light condition,the dawn simulation light resulted in a significant improvement of subjective alertness and positive mood after wakeup.Similarly,response time on PVT and accuracy on go/no-go task were much faster and higher respectively in the artificial dawn condition relative to the control and constant light.However,the light conditions had no differential effects on negative mood and the 2-back task.These findings suggest that morning sleep inertia has a significant negative effect on subjective alertness and positive affect as well as some cognitive functions like sustained attention,working memory and inhibitory capacity.The simulated dawn light could help counteract sleep inertia after awakening in the morning,whose effect was highly related to the light pattern with a dynamic exponential change.