Paper Selected From Thousands of Journal Articles Published in 2010

Research led by Rensselaer Polytechnic Institute Associate Professor Mariana Figueiro on the impact of light on teenagers’ sleeping habits was selected for publication in Best of Sleep Medicine 2011. The textbook is designed to keep sleep clinicians, researchers, and technologists informed of the latest science and technology advances in the growing field of sleep medicine.

According to Editor Dr. Teofilo Lee-Chiong of National Jewish Health, Best of Sleep Medicine 2011 covers the entire spectrum of adult and pediatric sleep sciences and is designed to represent some of the finest scientific literature on sleep medicine published in 2010. The articles are selected from among thousands of journal articles in medicine, neurology, psychiatry, and surgery periodicals. The book contains concise summaries of the notable works accompanied by commentaries written by major international authorities on sleep medicine.  

Figueiro, Light and Health Program director at the Rensselaer Lighting Research Center (LRC), led a series of field studies examining the impact of light on teenagers’ sleeping habits.  The paper selected for publication in Best of Sleep Medicine 2011 details results from one of those studies where the LRC research team 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 the onset of melatonin, the hormone that indicates to the body when it’s nighttime, according to Figueiro.  The human circadian system is maximally sensitive to blue light, therefore removal of morning blue light can reduce synchronization of the sleep/wake cycle to the 24-hour solar day.

The details of the study were summarized in the paper “Lack of short-wavelength light during the school day delays dim light melatonin onset (DLMO) in middle school students,” by Figueiro and LRC Director Mark Rea, and published by the journal Neuroendocrinology Letters 2010: 31 (1).

The series of field studies examined 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.

“The field studies supported the research team’s general hypothesis that the entire 24-hour pattern of light/dark exposure influences synchronization of the body’s circadian clock with the solar day and thus influences teenagers’ sleep/wake cycles,” said Figueiro. “As a general rule, teenagers should increase morning daylight exposure year round and decrease evening daylight exposure in the spring to help ensure they will get sufficient sleep before going to school.”  

In the series of studies, each subject wore a Daysimeter, a small, head-mounted device developed by the LRC to measure an individual’s exposure to daily “circadian light,” as well as rest and activity patterns. The definition of circadian light is based upon the potential for light to suppress melatonin synthesis at night, as opposed to measuring light in terms of how it stimulates the visual system.

The studies, sponsored by the U.S. Green Building Council (USGBC) and, in part, by a grant from a Trans-National Institutes of Health Genes, Environment and Health Initiative (NIH-GEI), were able to relate field measurements of circadian light exposures to a well-established circadian marker—evening melatonin levels. 

To read more about LRC field studies, visit http://www.lrc.rpi.edu/programs/lightHealth/projects/K12light.asp.

Best of Sleep Medicine 2011 is available at http://www.amazon.com/Best-Sleep-Medicine-2011-Collection/dp/1460993853.