Teens combat morning blahs with 'blue' light.

• Position: Sleep Deprivation - Short-wavelength light

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 and Prevention, Atlanta, Ga., almost 70% of schoolchildren get insufficient sleep--less than eight hours on school nights. This type of restricted sleep schedule has been linked with depression, behavior problems, poor scholastic performance, drug use, and automobile accidents. A study from the Lighting Research Center at Rensselaer Polytechnic Institute, Troy, N.Y., 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.

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, cortisol levels rise sharply within the first 30 to 60 minutes after waking. This is known as the...