Adolescent sleep delay: circadian regulation and phase shifting with light

描述(由申请人提供)：这项提案的主要目的是研究青少年的昼夜节律(~24小时)系统及其与成人相比对光的相移反应。青少年通常报告睡觉时间晚了，晚上往往最警觉，这些行为在一定程度上是由内源性生物钟驱动的。睡眠和觉醒的昼夜节律提示在青少年时期较晚。不幸的是，这种晚睡模式不谋而合 高中的开学时间比较早。因此，许多高中生(14-17岁)面临着晚睡的生理冲动和醒来的社交冲动的矛盾。 很早就上学了。由此产生的睡眠限制与一系列负面后果有关，包括学习成绩不佳，情绪低落的风险增加，以及白天警觉性下降。强光能够相移(重置)生物钟，因此可以帮助青少年适应早早的学校睡眠/起床时间表。商业化的灯箱可以在家中用于治疗；然而，必须具有对光的相位响应曲线(PRC)，以了解强光照射的最佳时间和避免在所需方向上产生最大相移。当在24小时内的不同时间呈现刺激(例如，强光)时，PRC图形化地说明了它的相移响应。目前，对于年轻的成年人来说，有几个可用于照明的PRC，但对于青少年来说，没有光的PRC存在。成人光PRC是否适合指导青少年的光治疗仍未得到测试。我们的目标是为14-17岁的青少年提供PRC to Light，为35至45岁的成年人提供PRC to Light。通过这样做，我们将检验这一假设，即与成年人相比，青少年对光表现出较小的相位提前反应和/或较大的相位延迟反应。我们还将检验这一假设，即与成年人相比，青少年表现出更长的自由奔跑昼夜节律。参与者将完成两个为期5天的平衡实验室课程。每一阶段都以唾液褪黑素采样开始和结束，以确定生物钟的相移。在此期间，参与者保持一个极端的明/暗时间表(睡2小时，醒2小时)，持续3天。在一个阶段中，没有给予刺激，昼夜节律系统自由运行，产生内源性昼夜节律周期。另一种是，在昼夜节律的不同时间点，每天开启一次明亮的光刺激。在亮光后产生的相移被校正为个体的自由运行周期，并相对于光管理绘制 是时候产生临立会了。这项研究可能会进一步加深我们对与青春期睡眠迟缓相关的昼夜节律因素的理解。此外，从这项研究产生的光的PRCs将在相移昼夜节律和治疗这些年龄段的基于昼夜节律的睡眠障碍方面具有直接和实际的应用。

DESCRIPTION (provided by applicant): The broad aim of this proposal is to examine the adolescent circadian (~24-hour) system and its phase shifting responses to light in comparison to adults. Adolescents often report late bedtimes and a tendency to be most alert in the evening, behaviors that are partly driven by the endogenous circadian clock. The circadian cue for sleep and wake initiation is late during the teen years. Unfortunately, this late sleep pattern coincides with the early start time of high school. Thus, many adolescents in high school (aged 14-17 years) are faced with a conflicting biological drive to fall asleep late and a social drive to wake early for school. The resulting sleep restriction is associated with a number of negative outcomes, including poor academic grades, an increased risk for depressed mood, and decrements in daytime alertness. Bright light is able to phase shift (reset) the circadian clock, and thus could help youngsters adjust to their early school sleep/wake schedule. Commercially available light boxes could be used at home for treatment; however, it is essential to have a phase response curve (PRC) to light to know the optimal times of bright light administration and avoidance to produce the maximum phase shift in the desired direction. PRCs graphically illustrate the phase shifting response to a stimulus (e.g., bright light) when it is presented at different times across the 24-hour day. Currently, there are several PRCs to light for young adult humans, but no light PRC exists for adolescent humans. It remains untested whether the adult light PRC is appropriate to guide light treatment in adolescents. We aim to generate a PRC to light for adolescents aged 14-17 years and a PRC to light for adults aged 35 to 45 years. By doing so, we will examine the hypothesis that adolescents manifest smaller phase advance responses and/or larger phase delay responses to light compared to adults. We will also examine the hypothesis that adolescents manifest a longer free-running circadian period compared to adults. Participants will complete two counterbalanced 5-day laboratory sessions. Each session begins and ends with salivary melatonin sampling to determine the phase shift of the circadian clock. In between, participants keep an ultradian light/dark schedule (sleep for 2 h and wake for 2 h) for 3 days. In one session, no stimulus is given and the circadian system free-runs yielding the endogenous circadian period. In the other, a bright light stimulus is turned on once per day at various points of the circadian cycle. Resulting phase shifts after bright light ar corrected for an individual's free-running period, and are plotted relative to light administration time to generate the PRCs. This study may further our understanding of circadian factors associated with late sleep patterns during adolescence. Furthermore, PRCs to light generated from this study will have direct and practical applications for phase shifting circadian rhythms and treating circadian-based sleep disorders in these age groups.