Scheuermaier Karine, Münch Mirjam, Ronda Joseph M, Duffy Jeanne F
Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Boston, MA, United States; Division of Sleep Medicine, Harvard Medical School, Boston, MA, United States; Wits Sleep Laboratory, Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Boston, MA, United States; Division of Sleep Medicine, Harvard Medical School, Boston, MA, United States; Sleep research and clinical chronobiology, Institute of Physiology, Charité Universitätsmedizin, Berlin, Germany; Clinic for Sleep and Chronomedicine, St. Hedwig-Krankenhaus, Berlin, Germany.
Behav Brain Res. 2018 Aug 1;348:267-275. doi: 10.1016/j.bbr.2018.04.021. Epub 2018 Apr 21.
Exposure to light can have acute alerting and circadian phase-shifting effects. This study investigated the effects of evening exposure to blue-enriched polychromatic white (BEL) vs. polychromatic white light (WL) on sleep inertia dissipation the following morning in older adults.
Ten healthy older adults (average age = 63.3 yrs; 6F) participated in a 13-day study comprising three baseline days, an initial circadian phase assessment, four days with 2-h evening light exposures, a post light exposure circadian phase assessment and three recovery days. Participants were randomized to either BEL or WL of the same irradiance for the four evening light exposures. On the next mornings at 2, 12, 22 and 32 min after each wake time, the participants completed a 90-s digit-symbol substitution test (DSST) to assess working memory, and objective alertness was assessed using a wake EEG recording. DSST and power density from the wake EEG recordings were compared between the two groups.
DSST performance improved with time awake (p < 0.0001) and across study days in both light exposure groups (p < 0.0001). There was no main effect of group, although we observed a significant day x group interaction (p = 0.0004), whereby participants exposed to BEL performed significantly better on the first two mornings after light exposures than participants in WL (post-hoc, p < 0.05). On those days, the BEL group showed higher EEG activity in some of the frequency bins in the sigma and beta range (p < 0.05) on the wake EEG.
Exposure to blue-enriched white light in the evening significantly improved DSST performance the following morning when compared to polychromatic white light. This was associated with a higher level of objective alertness on the wake EEG, but not with changes in sleep or circadian timing.
暴露于光线下会产生急性警觉和昼夜节律相移效应。本研究调查了老年人在夜间暴露于富含蓝光的多色白光（BEL）与多色白光（WL）下对次日早晨睡眠惯性消散的影响。
10名健康老年人（平均年龄 = 63.3岁；6名女性）参与了一项为期13天的研究，包括3天基线期、一次初始昼夜节律相位评估、4天每天2小时的夜间光照暴露、光照暴露后的昼夜节律相位评估以及3天恢复期。在4次夜间光照暴露中，参与者被随机分配到相同辐照度的BEL或WL组。在每次醒来后的第2、12、22和32分钟，参与者完成一项90秒的数字符号替换测试（DSST）以评估工作记忆，并使用清醒脑电图记录评估客观警觉性。比较两组之间的DSST和清醒脑电图记录的功率密度。
在两个光照暴露组中，DSST表现均随着清醒时间的延长（p < 0.0001）和整个研究天数的增加而改善（p < 0.0001）。尽管我们观察到显著的天数×组间交互作用（p = 0.0004），但没有组间主效应，即暴露于BEL的参与者在光照暴露后的前两个早晨的表现明显优于WL组的参与者（事后检验，p < 0.05）。在那些日子里，BEL组在清醒脑电图的某些西格玛和贝塔范围内的频率区间显示出更高的脑电图活动（p < 0.05）。
与多色白光相比，夜间暴露于富含蓝光的白光下可显著改善次日早晨的DSST表现。这与清醒脑电图上更高水平的客观警觉性相关，但与睡眠或昼夜节律时间的变化无关。
