Reference
van der Lely S, Frey S, Garbazza C, et al. Blue blocker glasses as a countermeasure for alerting effects of evening light-emitting diode screen exposure in male teenagers. J Adolesc Health. 2015;56(1):113-119.
Design
The study lasted for 16 days and was organized in 2 parts in a balanced crossover design separated by a period of at least 1 week up to a maximum of 5 weeks. Each study part consisted of a 15.5-hour stay in the laboratory.
Participants
Thirteen healthy male high-school students between 15 and 17 years old (mean age=16.5 y) took part in this study.
Study Intervention
During the week preceding their testing in the lab, participants wore either orange-tinted glasses designed to block blue wavelengths of light or similar glasses with clear lenses from 6:00 PM until they went to bed. The glasses were switched in a crossover, counterbalanced design. A device to measure and record light exposure was attached to the glasses. Participants kept a log of how long they wore the glasses and their use of illuminated screens.
Outcome Measures
Rest-activity cycles during the week prior to the study night were measured by an Actiwatch (Phillips Healthcare, Eindhoven, the Netherlands) worn on the wrist.
At the end of each “test week,” participants reported to the lab 5.5 hours before their normal sleep time. During the first 2 hours of the protocol, they sat in dim light (<8 lx) followed by dark adaptation for 30 minutes. Then they sat for 3 hours in front of a light-emitting diode (LED) computer screen wearing either the orange blue-blocker glasses or glasses with clear lenses. Lights in the lab were turned off, and the LED screen was set to a white background. During the test session, participants completed several cognitive assessments and every 30 minutes they provided saliva samples that were tested for the presence of melatonin. After 3 hours of LED exposure, participants went to sleep, and polysomnographic recordings were collected during the 8-hour sleep period. In the morning, similar cognitive testing was performed.
Key Findings
During the week when the boys wore their orange-tinted glasses in the evening, they felt “significantly more sleepy” than when they wore clear glasses. The blue-blocking/orange glasses decreased LED screen–induced melatonin suppression and modulated subjective sleepiness and vigilance attention levels in the late evening hours. Wearing the orange glasses was associated with a reduction in subjective and cognitive activation.
Practice Implications
This is an interesting tool to consider for sleep-deprived, night-owl adolescents—your basic average teenager. This may also be an interesting tool to consider for cancer patient use.
Human adolescents are so well known for having poor sleep quality, insufficient sleep duration, and daytime sleepiness that it seems redundant and hardly necessary to add a citation, but here is one anyway.1 These sleep problems lead to emotional instability, impaired daytime function, and poor school performance.2 These kids are going through a fundamental developmental shift of their internal clocks located in the suprachiasmatic nuclei (SCN) of the hypothalamus so that they will be more alert in the evening. They want to delay going to sleep at night and stay asleep later in the morning,3 and the older they get, the worse this tendency becomes.4 Between 0.5% and 16% of kids with this tendency develop sleep-related problems5 that negatively impact their home, school, and work lives. Even kids with good intentions regarding daytime wakefulness are doomed by their own developmental changes; they simply take longer to build up sleep need, which increases wakefulness at night and sleepiness in the morning. It is no surprise that they end up tired during the day.6 This situation isn’t made easier by modern lifestyles, including school, social, and sporting activities.7
Light is humanity’s most important Zeitgeber, the synchronizer of our circadian clocks, and the modern use of light-emitting diode screens is causing confusion in those suprachiasmatic nuclei of our teenagers.
If all this wasn’t challenging enough, we have entered a new phase in human evolution: the era of artificial light from electronic sources. The multimedia screens that light our computers, televisions, and phones provide a physiological challenge that teens are ill prepared for. Light is humanity’s most important Zeitgeber, the synchronizer of our circadian clocks, and the modern use of LED screens is causing confusion in those SCN of our teenagers.
A study published in the British Medical Journal reported that the more screen time teens engage in, the longer it takes them to fall asleep at bedtime. The teens in this study said they needed between 8 and 9 hours of sleep on average to feel rested. Those with 4 or more hours of screen time per day were 350% more likely to sleep less than 5 hours at night. They also were 49% more likely to need more than 60 minutes to fall asleep. Adults normally fall asleep in under 30 minutes.8
The story behind the orange glasses
In 2001 Skene and colleagues reported that some wavelengths of light had more effect than others at suppressing melatonin. The shorter wavelengths of light, what we perceive as dark blue, suppressed melatonin the most.9 Skene pointed out in a New York Times article, “Devices such as smartphones and tablets are often illuminated by light-emitting diodes, or LEDs, that tend to emit more blue light than incandescent products. Televisions with LED backlighting are another source of blue light, though because they are typically viewed from much farther away than small screens like phones, they may have less of an effect.”10
In 2002, Berson et al reported they had isolated the specific photoreceptors, a type of retinal ganglion cell, that regulate melatonin. These cells extend into a part the SCN and transmit information directly from the eyes.11,12 In 2003, Lockley showed that these receptors were most sensitive to a specific color of blue light; 460 nm wavelength suppresses melatonin to twice the degree as 555 nm light does.13
In 2005, Cajochen reset the circadian clocks of study participants by using colored lights.14 At about this time, we all started seeing advertisements and reports that wearing special glasses designed to filter out blue light was proving useful in treating sleep disturbances. In 2008, Phelps reported success in stabilizing teenaged bipolar patients with these blue-blocking lenses.15 Earlier papers had recommended enforced bed rest and keeping these patients in pitch dark rooms,16 so wearing the glasses was a simpler solution.
In 2014, a case report by Henrikson et al described a rapidly cycling bipolar patient who took part in a simple experiment. For the first 7 days of treatment, he wore clear glasses in the evening. This had no effect. On day 9, he switched to blue-blocking lenses for the next week; the researchers reported,
The transition to the blue-blocking regime was followed by a rapid and sustained decline in manic symptoms accompanied by a reduction in total sleep, a reduction in motor activity during sleep intervals, and markedly increased regularity of sleep intervals. The patient's total length of hospital stay was 20 days shorter than the average time during his previous manic episodes.17
In a 2009 paper, Burkhardt and Phelps compared the true blue-blocking glasses with placebo lenses, using as the placebo yellow-tinted safety glasses sold in hardware stores. Twenty adult volunteers wore the glasses for 3 hours each evening. After 3 weeks, only those with the true blue-blocking lenses reported significantly improved sleep compared to the controls.18
The most intriguing of the possibilities suggested in the medical literature is that these glasses may reduce cancer risk. It is well established that disruption of a normal circadian rhythm increases cancer risk. Wearing these glasses in the evening may prevent this disruption.19
