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LD+A The Magazine of the Illuminating Engineering Society of North America

Lighting Research & Education  

Short-Wavelength Light Can Help Teenagers


Sleep-starved teens may be able to rest easier, according to new research from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute. The LRC study indicates that exposure to short-wavelength blue light in the morning has the potential to help sleep-deprived adolescents prepare for the challenges of the day and deal with stress. Levels of cortisol, a hormone produced by the adrenal gland, follow a daily 24-hour rhythm. Cortisol concentrations are low throughout the day, reaching a broad minimum in the evening before rising slowly again through the night. In addition to this gradual elevation of cortisol at night, cortisol levels rise sharply within the first 30 to 60 minutes after waking. This is called cortisol awakening response (CAR), and a high CAR has been associated with better preparedness.

LRC’s study included three overnight sessions, at least one week apart. Adolescents aged 12 to 17 wore a dimesimeter to measure light exposure and went to sleep at 1:30 am and woke up at 6:00 am, a 4.5-hour sleep opportunity. Each week, participants either experienced morning short-wavelength blue light or remained in dim light. Results showed that exposure to short-wavelength blue light in the morning significantly enhanced CAR in sleep deprived adolescents, more so than dim light.

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