Exposure to short-wavelength “blue” light in the morning helps sleep-deprived teens combat stress, a new study has found.
The study by the Rensselaer Polytechnic Institute, New York shows that morning light exposure may help to wake up the body when it is time to be active, thus preparing individuals for any environmental stress they might experience.
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 30-60 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.
“The present results are the first to show that low levels of short-wavelength light enhance CAR in adolescents who were restricted from sleep,” said researcher Mariana Figueiro.