Debbie Nicholson

Short-wavelength blue light may help teens get ready for the days challenges and stresses

An online study in June of this year released by the CDC revealed 70 percent of high school students are not getting the recommended hours of sleep (8.25 to 9.25) and are actually receiving less than eight hours a night.

The information on sleep for the study came from data gathered from the 2007National Health Behavior Survey in which students responded to questions about how many hours an average of sleep do they get on a school night. Sufficient sleep was noted as eight hours or more a night. On an average school night nearly 70 percent reported insufficient sleep.

View slideshow: Blue Light Therapy

Insufficient sleep is associated to numerous risky behaviors including alcohol and tobacco usage, fighting, sedentary behavior and being sexually active.

Lack of sleep in teens has been linked to insulin resistance, increased risk for heart disease, depression and mental health issues.

A clinical study published in the International Journal of Endocrinology shows morning short-wavelength blue light improves cortisol awakening response in sleep restricted adolescents resulting in them being better prepared for the day’s challenges and any environmental stress they may encounter.

Levels of cortisol, a hormone produced by the adrenal gland follow a daily 24 hour rhythm reaching minimal levels in the evening and peaking near wake-up time. Cortisol levels also hit a sharp rise in concentration within the first hour after waking referred to as cortisol awakening response or CAR for short according to the study’s abstract. A high CAR has been associated having better preparation for stressful and challenging events.

Research has shown that blue light exceeds other colors of light when it comes to resetting the body’s internal clock.

‘This study is a secondary analysis of a larger study in which investigated the impact on short-wavelength light on sleep restricted adolescents. This study was conducted over the course of three over night session at least one week apart consisting of 18 adolescents aged 12 to 17 years.

Participants had slept for four and half hours from 1:30 am to 6:30 am. Each week participants were either exposed to short-wave length blue light (40 lux of 470-nanometer light) for 80 minutes after waking or exposed to dim light. Salvia samples were collected to asses CAR.

In order for the experts to observe light exposure all participants had worn a Dimesimeter (a small calibrated light meter device developed by the LRC that continuously records circadian light and activity levels) on a wrist band.

In conclusion Dr. Mark Rea, PhD, LRC (Lighting Research Center) Director and professor of cognitive sciences stated "We found that exposure to short-wavelength blue light in the morning significantly enhances CAR in sleep deprived adolescents, more so than dim light.” "Morning exposure to short-wavelength light may be a simple, yet practical way to better prepare adolescents for the challenges of the day."

Dr. Rea collaborated on this study with Dr. Mariana Figueiro, PhD, Program Director and associate professor at LRC.

The researchers also in addition to their data they tentatively suggest that reduced evening light exposure may also influence CAR. Further studies should be conducted to confirm these findings.

LRC researchers also studied the effects of “blue light treatment” on seniors with and without Alzheimer’s disease (AD) in a nursing facility in upstate New York.

Persons with Alzheimer’s disease are especially affected by sleep problems and frequently waking during the night.

‘During the four week study residents were exposed to tabletop LED luminaires for two hours each day from 4:30 pm to 8:30 pm.

For the first two weeks one group of residents with and without AD were exposed to blue LED and the other group of residents with and without AD were exposed to red LED (used as placebo control).

After a short break, the second two-week phase of the experiment began. The residents exposed to blue light in the first phase were exposed to red light in the second phase, and vice versa.

During the study researchers had analyzed the percentage of time the residents had slept between midnight and 6 am. The study revealed statistically significant increases in sleep after the blue light treatment of all residents.

The results also showed non-AD residents remained asleep 90% of the time between midnight and 8 am after blue light treatment and only 67% of the time after red light treatment. AD residents exposed to blue light treatment had remained asleep 67% of the time compared to those exposed to red light at 54% of the time.

More information on light and health can be found online at the Lighting Research Center website.