Kids these days. They haven’t got it easy. According to the Center for Disease Control, almost 70% of school children don’t get their full 8 hours of sleep on most school nights. Whether this is due to heavy workloads, intense extracurriculars, goofing off, or simply having an overactive mind, the resulting problems are the same. Inadequate sleep has been linked to things like depression, behavioral problems, poor academic performance, drug use, and car accidents.
However, a recent study led by Mariana Figueiro and Mark S. Rea of the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute may have found an unexpected remedy for stressed, sleep-deprived kids: blue light.
To understand the study, first we need to know a little bit about the human body.
The Cortisol Awakening Response
The hormone cortisol, produced by the adrenal gland, operates on a 24-hour cycle, helping regulate our bodies navigate in and out of sleep. Concentrations of cortisol reach a minimum at bedtime and a peak in the morning. Levels hit their max in the first hour of waking, this is called the Cortisol Awakening Response or CAR.
Experts associate a high CAR with better preparedness for the stresses and challenges of the day.
So how the heck does blue light factor in? Well, we’ve already seen how short-wavelength light can suppress melatonin to keep you awake at night (read more on that here), so it’s not surprising that it has an influence on us in the morning.
The study conducted 3 overnight sessions, spaced out with at least a week between each. In these sessions, adolescents aged 12-17 were allowed to sleep only 4.5 hours at night. Each subject’s activity levels and light exposure were measured with a Dimesimeter, a monitoring device worn on the wrist. In the morning, participants experienced either short-wavelength blue light or dim light.
Researchers collected saliva samples from the test subjects over 20 minute increments after the subjects awoke, to measure their CARs. The study found that those exposed to the short-wavelength light in the morning had significantly enhanced CARs compared to those in dim light.
In the end, the study determined that morning exposure to short-wavelength light is a simple, practical way to prepare for an active day and manage stress.
The complete results were recently published in the International Journal of Endocrinology. You can view them in full here.