Starting School Later Is Not Enough

Recent conclusions by scientists at the University of Surrey, UK and Harvard University published in Scientific Reports on March 27, 2017, are very important for researchers, parents, and educators who are concerned about the effects of sleep insufficiency in children and adolescents. They present results of mathematical modeling of shifting sleep-wake cycles, and at the end of the Discussion section, they state:

"Our work confirms and implies that: we should educate teachers, parents, and students on sleep hygiene and the role of light; that we should advocate brighter light in classrooms and offices, or access to natural light in the morning; that we should minimize light in the evening as far as possible; and that light interventions may be more effective at reducing social jet-lag than changing school/work start-times."

While evidence for the detrimental effects of too little sleep has been accumulating for decades, attention to the problem has been brought into sharp focus by the debates surrounding the ideal times to start the school day. Around the U.S., a great number of school districts are deliberating the pros and cons of pushing school start times later in the morning for adolescents. The assumption is that starting school later will give adolescents the opportunity to attain more sleep that will in turn lead to more optimal school performance, fewer problems with emotion regulation, and better health outcomes.

I count myself among the child and adolescent sleep researchers who are in favor of later school start times. Yet I have also warned against unrealistic expectations that changing start times without additional measures will necessarily lead to the desired outcomes. Numerous parents have asked whether or not adolescents will simply stay up later if they are able to wake later on school days. The obvious answer is that many may definitely do so. The research of Skeldon et al. (2017) suggests that even if they can sleep later in the morning, unless they limit exposure to light from screens (TV, computer, phones) in the evening, their circadian timing will simply shift later and they will not sleep any longer than previously.

The article begins with a very good explanation of how sleep timing has changed with modernization allowing human societies to extend the period of wake time through the use of artificial lighting. The sleep patterns of contemporary hunter-gathering societies (e.g. Hazda and San people in Africa) are comparable to those that ancestral humans had for millennia. They rise around dawn, are exposed to high levels of natural light, and sleep relatively early in the evening in environments that are very dark. Increasingly, and especially in the last few years, those of us living in high technology societies are exposing ourselves to light later and later into the evening. No matter what time school starts, children should limit exposure to artificial light in the evening to allow natural melatonin to induce sleepiness. Apps are available for many phones and some have built-in settings that shift screen light away from the blue spectrum. Devices are also available for LED computer and TV screens. But putting the phone away works even better!

In reference to school start times, the authors state that schools in the UK typically begin between 8:30 and 9:00 AM and some are recommending that they shift later to between 9:30 and 10:00 AM. They hasten to add that because U.S. schools begin earlier, some before 8:00 AM, pushing those times later seems advisable. Even the strongest advocates of later school start times likely realize that while starting later is a necessary step, making that change is not sufficient in itself to increase children’s sleep. The research of Skeldon et al. (2017) is a welcome reminder of that fact and provides useful suggestions for what some of those further steps should be.

http://www.nature.com/articles/srep45158#f1