Carskadon M A, Wolfson A R, Acebo C, Tzischinsky O, Seifer R
Sleep Research Laboratory, E.P. Bradley Hospital, E. Providence, RI 02915, USA.
Sleep. 1998 Dec 15;21(8):871-81. doi: 10.1093/sleep/21.8.871.
This study examined effects on adolescent sleep patterns, sleepiness, and circadian phase of a school transition requiring an earlier start.
Adolescents were evaluated in 9th and 10th grades; school start time in 9th grade was 0825 and in 10th grade was 0720. Assessments at each point included 2 weeks of actigraphy and sleep diaries at home, followed by a 22-hour laboratory evaluation, including evening saliva samples every 30 minutes in dim light for determination of dim-light salivary melatonin onset phase (DLSMO), overnight sleep monitoring, and multiple sleep latency test (MSLT).
Twenty-five females and 15 males, ages 14 to 16.2 were enrolled; 32 completed the study in 9th grade and 26 completed in 10th grade.
Participants kept their own schedules, except that laboratory nights were scheduled based upon school-night sleep patterns.
According to actigraphy, students woke earlier on school days in 10th than in 9th grade, but they did not go to sleep earlier and they slept less. DLSMO phase was later in 10th grade (mean = 2102) than 9th grade (mean = 2024). Sleep latency on MSLT overall was shorter in 10th (mean = 8.5 minutes) than in 9th (mean = 11.4 minutes), particularly on the first test of the morning at 0830 (5.1 vs 10.9 minutes). Two REM episodes on MSLT occurred in 16% of participants in 10th grade; one REM episode occurred in 48%. When those with REM sleep on one or both morning MSLTs (n = 11) were compared to those without morning REM, significant differences included shorter sleep latency on the first test, less slow wave sleep the night before, and later DLSMO phase in those who had morning REM.
Early start time was associated with significant sleep deprivation and daytime sleepiness. The occurrence of REM sleep on MSLT indicates that clinicians should exercise caution in interpreting MSLT REM sleep in adolescents evaluated on their "usual" schedules. Psychosocial influences and changes in bioregulatory systems controlling sleep may limit teenagers' capacities to make adequate adjustments to an early school schedule.
本研究考察了学校上课时间提前对青少年睡眠模式、困倦程度和昼夜节律相位的影响。
对青少年在九年级和十年级时进行评估；九年级上课时间为08:25，十年级上课时间为07:20。每个时间点的评估包括在家进行为期2周的活动记录仪监测和睡眠日记记录，随后进行一次22小时的实验室评估，包括在昏暗灯光下每30分钟采集一次夜间唾液样本以测定暗光唾液褪黑素起始相位（DLSMO）、整夜睡眠监测以及多次睡眠潜伏期测试（MSLT）。
招募了25名女性和15名男性，年龄在14至16.2岁之间；32人完成了九年级的研究，26人完成了十年级的研究。
参与者保持自己的日程安排，但实验室夜间安排基于上学日的睡眠模式。
根据活动记录仪监测，十年级学生上学日比九年级学生醒得更早，但入睡时间没有提前，睡眠时间也更少。十年级的DLSMO相位（平均 = 21:02）比九年级（平均 = 20:24）更晚。十年级MSLT的总体睡眠潜伏期（平均 = 8.5分钟）比九年级（平均 = 11.4分钟）更短，尤其是在早上08:30的第一次测试中（5.1分钟对10.9分钟）。十年级16%的参与者在MSLT中有两次快速眼动（REM）睡眠期发作；48%的参与者有一次REM睡眠期发作。将早上一次或两次MSLT中有REM睡眠的参与者（n = 11）与早上没有REM睡眠的参与者进行比较，显著差异包括第一次测试的睡眠潜伏期更短、前一晚的慢波睡眠更少以及有早上REM睡眠的参与者的DLSMO相位更晚。
上课时间提前与严重的睡眠剥夺和白天困倦相关。MSLT中出现REM睡眠表明，临床医生在解释按青少年“常规”日程安排进行评估时的MSLT REM睡眠时应谨慎。心理社会影响以及控制睡眠的生物调节系统的变化可能会限制青少年对提前上学日程做出充分调整的能力。
