Lack of morning light keeping teenagers up at night

Zoe Caira wears a personal light-measuring device, called a Daysimeter, to monitor her rest and activity patterns and the amount of circadian light -- short-wavelength (blue) light -- reaching her eyes. Credit: Rensselaer Polytechnic Institute

Rensselaer Polytechnic Institute recently conducted a field study to learn the effects of morning light on teenagers' sleep cycles. They concluded that a lack of exposure to early morning light can result in a 30-minute delay in the onset of sleep.

"If you remove blue light in the morning, it delays the onset of melatonin, the hormone that indicates to the body when it's nighttime," explains Dr. Figueiro. "Our study shows melatonin onset was delayed by about 6 minutes each day the teens were restricted from blue light. Sleep onset typically occurs about 2 hours after melatonin onset."

The study findings should have significant implications for school design. "Delivering daylight in schools may be a simple, non-pharmacological treatment for students to help them increase sleep duration," concludes Dr. Figueiro.

The new research has applications for more than 3 million shift workers and Alzheimer's patients who suffer from lack of a regular sleep pattern.

Studies have shown that this lack of synchronization between a shift worker's rest and activity and light/dark patterns leads to a much higher risk of cardiovascular disease, diabetes, seasonal depression and cancer over decades.

Lack of morning light keeping teenagers up at night