“As teenagers spend more time indoors, they miss out on essential morning light needed to stimulate the body’s 24-hour biological system, which regulates the sleep/wake cycle,” reports Mariana Figueiro, assistant professor and program director at Rensselaer’s Lighting Research Center (LRC) and lead researcher on the new study.
“These morning-light-deprived teenagers are going to bed later, getting less sleep, and possibly under-performing on standardized tests. We are starting to call this the teenage night owl syndrome.”
In the study just published in Neuroendocrinology Letters, Figueiro and LRC Director Mark Rea found that 11 8th grade students who wore special glasses to prevent short-wavelength (blue) morning light from reaching their eyes experienced a 30-minute delay in sleep onset by the end of the five-day study.
“If you remove blue light in the morning, it delays the onset of melatonin, the hormone that indicates to the body when it’s nighttime,” explains Figueiro. “Our study shows melatonin onset was delayed by about six minutes each day the teens were restricted from blue light. Sleep onset typically occurs about two hours after melatonin onset.”
The problem is that today’s middle and high schools have rigid schedules requiring teenagers to be in school very early in the morning. These students are likely to miss the morning light because they are often traveling to and arriving at school before the sun is up or as it’s just rising. “This disrupts the connection between daily biological rhythms, called circadian rhythms, and the Earth’s natural 24-hour light/dark cycle,” she says.
In addition, the schools are not likely providing adequate electric light or daylight to stimulate this biological or circadian system, which regulates body temperature, alertness, appetite, hormones, and sleep patterns. Our biological system responds to light much differently than our visual system. It is much more sensitive to blue light. Therefore, having enough light in the classroom to read and study does not guarantee that there is sufficient light to stimulate our biological system.
“According to our study, however, the situation in schools can be changed rapidly by the conscious delivery of daylight, which is saturated with short-wavelength, or blue, light,” reports Figueiro.
Her research, sponsored by the U.S. Green Building Council and in part by a grant from a Trans-National Institutes of Health Genes, Environment and Health Initiative, is the first field study to measure the impact of reduced morning blue light exposure on evening melatonin onset of teenagers attending school.
The field experiment was conducted at Smith Middle School in Chapel Hill, N.C., a school with good daylight design. The school building has south-facing skylights to deliver daylight to nearly all interior spaces throughout the day.
The study detailed in Neuroendocrinology Letters is part of a larger study where data on students was collected at both Smith Middle School in Chapel Hill, as well as Algonquin Middle School in Averill Park, N.Y.
The larger study is examining not only the impact of removing morning blue light, but also the seasonal impact and the increased evening light exposure during the spring months on teens’ melatonin onset and sleep times.
Throughout her research, Figueiro has repeatedly come face-to-face with the enormous concern of parents over teenagers going to bed too late. “Our findings pose two questions: ‘How will we promote exposure to morning light and how will we design schools differently?’ ” says Figueiro.
The study findings should have significant implications for school design. “Delivering daylight in schools may be a simple, non-pharmacological treatment for students to help them increase sleep duration,” concludes Figueiro.
The new research has applications for more than three million shift workers and Alzheimer’s patients who suffer from lack of a regular sleep pattern.
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