Impacts of Later High School Start Times on Adolescent Weight and Weight-Related Behavior

 虽然美国国家睡眠基金会建议青少年每晚睡眠时间为8.5至9.25小时，但超过一半的美国16岁青少年经常少于7小时。“睡眠债”的后果远远超出了阻碍日常运作的范围，因为它对身体和心理健康的多个领域都是有害的。在 在肥胖症流行的背景下，睡眠不足正在成为过度体重增加和体重增加相关行为发展的潜在重要和新的危险因素，肥胖症流行已经对公共健康产生了深远的影响。虽然屏幕时间，家庭作业期望和其他因素等各种因素可能会阻碍美国青少年的睡眠，但研究表明，与青少年生物学不同步的早期高中开始时间是青少年能够获得充足睡眠的最重要障碍之一。当儿童开始青春期时，昼夜节律发生变化，使得褪黑激素在晚上晚些时候分泌，使得在晚上11点之前难以入睡。这种神经生物学上的变化意味着，那些参加“早开始”（上午8点30分之前）高中的青少年，即使是那些努力早睡的人，也会很难获得充足的睡眠。自然 实验已经清楚地表明，晚一点的开学时间可以让青少年有更多的机会积累充足的睡眠，但不幸的是，86%的美国学校在早上8点30分之前就开始上课了。我们假设，晚一点的开始时间，一个既定的有效的睡眠干预，可能会促进体重相关的健康。鉴于青春期是一个关键年龄，为长期肥胖风险行为模式奠定了基础，因此迫切需要了解干预和政策变化导致的睡眠增加对肥胖的影响。目前有一个独特的机会，研究一个以社区为基础的自然实验，在学校开始时间政策的修改。明尼阿波利斯圣保罗，明尼苏达州都会区学区，将改变其高中的开始时间从上午7时30分至上午8时30分在2016年秋季。我们建议收集学生体重和相关风险的数据（通过调查，客观的体重和身高测量，以及睡眠活动记录）在这个地区和高中学生在一个比较区，这将不会改变其上午7：30高中开始时间之前和之后的变化。这项研究具有时间敏感性，作为基线，政策前措施必须在2015/16学年结束前收集。我们的具体目标是：1）确定如何转移到更晚的高中开始时间与客观测量的体重变化随着时间的推移。2)确定学校开学时间和肥胖相关行为之间的关系。我们有一个额外的探索性目标，通过利益相关者访谈，评估与实施晚些时候高中开始时间相关的障碍和促进因素。这项研究的结果将对公共卫生产生影响，因为它们将澄清青少年睡眠和肥胖之间的因果关系，并为学校政策是否可以最大限度地减少不健康的体重增加提供证据。如果有效的话，推迟开学时间，这是一项可在美国各地社区部署的政策，可以帮助防止年轻人体重过度增加。

 DESCRIPTION (provided by applicant): Although the National Sleep Foundation recommends 8.5 to 9.25 hours of sleep per night for adolescents, more than half of US 16-year-olds regularly get less than seven hours. "Sleep debt" has consequences that extend far beyond hampering day-to-day functioning as it is deleterious to multiple areas of physical and mental health. In the context of the obesity epidemic, which has had a far-reaching public health impact, sleep insufficiency is emerging as a potentially important and novel risk factor for the development of excess weight gain and weight gain-related behaviors. While a variety of forces such as screen time, homework expectations, and other factors can be implicated in stymying American teenagers' sleep, research has shown that early high school start times, which are asynchronous with adolescent biology, are one of the most significant obstacles to youth being able to net sufficient sleep. When children begin puberty, circadian rhythms shift such that melatonin is secreted later in the evening making it difficult to fall asleep before 11pm. This neurobiological change means that adolescents who attend "early-start" (prior to 8:30am) high schools, even those who strive for an early bedtime, will struggle to get sufficient sleep. Natural experiments have clearly shown that later school starts allow adolescents a greater opportunity to accumulate adequate sleep, but unfortunately 86% of US schools start before 8:30am. We hypothesize that later start times, an established effective sleep intervention, may promote weight-related health. Given that adolescence is a critical age that sets the stage for long-term obesity risk behavior patterns, there is an urgent need to understand the obesity-related implications of increased sleep as a result of intervention and policy changes. Presently there is a unique opportunity to study a community- based natural experiment in school start time policy modification. A Minneapolis-St. Paul, MN metro area school district, will be shifting the start tim of its high school from 7:30am to 8:30am in Fall 2016. We propose to collect data on student weight and related risks (via survey, objective weight and height measurement, and sleep actigraphy) before and after this change in this district and high school students in a comparison district which will not be altering its 7:30am high school start time. This research is time-sensitive as baseline, pre-policy measures must be collected before the end of the 2015/16 school year. Our specific aims are: 1) Determine how a shift to a later high school start time relates to objectively measured weight change over time. 2) Identify the relationship between school start times and obesity-related behaviors over time. We have an additional exploratory aim to assess barriers and facilitators associated with implementing later high school start times via stakeholder interviews. The products of this research will have public health impact because they will clarify causal connections between sleep and obesity among adolescents as well as provide evidence for whether a school policy can minimize unhealthy weight gain. If effective, later school start times, a policy deployable in communities across the US, could help prevent excess weight gain in youth.