“Blue” light could help teenagers combat stress

Adolescents can be chronically sleep deprived because of their inability to fall asleep early in combination with fixed wakeup times on school days.

According to the Centers for Disease Control (CDC), almost 70 per cent of schoolchildren get insufficient sleep - less than eight hours on school nights. This type of restricted sleep schedule has been linked with depression, behaviour problems, poor performance at school, drug use, and automobile accidents.

A new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute shows that exposure to morning short-wavelength ''blue'' light has the potential to help sleep-deprived adolescents prepare for the challenges of the day and deal with stress, more so than dim light.

The study was a collaboration between associate professor and director of the LRC light and health programme Mariana Figueiro and LRC director and professor Mark S Rea. Results of the study, titled, ''Short-Wavelength Light Enhances Cortisol Awakening Response in Sleep-Restricted Adolescents,'' were recently published in the open access International Journal of Endocrinology.

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 throughout 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 known as the cortisol awakening response (CAR). In nocturnal animals, the cortisol spike occurs at night, at the start of activity. It appears to be associated with the time of transition from rest to activity, upon waking. A high CAR has been associated with better preparedness for stressful and challenging activities.