As many a parent would confirm, some teens would prefer to stay up all night, then sleep past noon –- every day.
Researchers have studied this behavior and now believe insufficient daily morning light exposure contributes to teenagers not getting enough sleep.
“As teenagers spend more time indoors, they miss out on essential morning light needed to stimulate the body’s 24-hour biological system, which regulates the sleep/wake cycle,” reports Mariana Figueiro, Ph.D., lead researcher on the new study.
“These morning-light-deprived teenagers are going to bed later, getting less sleep and possibly under-performing on standardized tests. We are starting to call this the teenage night owl syndrome.”
In the study just published in Neuroendocrinology Letters, Dr. Figueiro and Dr. Mark Rea found that eleven 8th grade students who wore special glasses to prevent short-wavelength (blue) morning light from reaching their eyes experienced a 30-minute delay in sleep onset by the end of the 5-day study.
“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.”
Disrupting Biological Rhythms
The problem is that today’s middle and high schools have rigid schedules requiring teenagers to be in school very early in the morning. These students are likely to miss the morning light because they are often traveling to and arriving at school before the sun is up or as it’s just rising.
“This disrupts the connection between daily biological rhythms, called circadian rhythms, and the earth’s natural 24-hour light/dark cycle,” explains Dr. Figueiro.
In addition, the schools are not likely providing adequate electric light or daylight to stimulate this biological or circadian system, which regulates body temperature, alertness, appetite, hormones and sleep patterns.
Our biological system responds to light much differently than our visual system. It is much more sensitive to blue light.
Therefore, having enough light in the classroom to read and study does not guarantee that there is sufficient light to stimulate our biological system.
“According to our study, however, the situation in schools can be changed rapidly by the conscious delivery of daylight, which is saturated with short-wavelength, or blue, light,” reports Dr. Figueiro.