Nighttime blue-light exposure inculpated in robbed sleep.

Blue-blockers’ resurgence as a sleep aid?

Don't call it a comeback-those bulky, amber-tinted sunglasses of infomercial fame have been here for years, but recent research takes blue blockers beyond '90s fad to potential sleep savior.

"Cellular telephone, tablet and personal computer use before bedtime can delay sleep onset, degrade sleep quality and impair alertness the following day."

Published in the Journal of Psychiatric Research, a study from the Columbia University Medical Center found amber-tinted lenses worn two hours preceding bedtime helped insomniacs gain an extra 30 minutes of sleep compared to clear lenses. Although a small-scale study, such research supports recent evidence that blue light exposure prior to sleep disrupts the body's circadian rhythm, delaying sleep onset and affecting duration.

Per the study, researchers recruited 14 individuals with insomnia for a multi-week controlled trial. For seven consecutive nights, participants wore wraparound, blue-light-blocking glasses for two hours prior to bedtime. Then, four weeks later, the trial was repeated with clear, placebo lenses. Participants wore wrist-actigraphy and were administered daily post-sleep questionnaires.

In addition to the 30 minutes of extra sleep, participants wearing the amber-tinted lenses self-reported greater sleep duration, quality and soundness of sleep, and reduction in insomnia severity on the Pittsburgh Insomnia Rating Scale as compared to the clear lenses. So, too, actigraphy measures of total sleep time were significantly higher in amber versus clear lenses, the study notes.

"These findings have health relevance given the broad use of light-emitting devices before bedtime and prevalence of insomnia," the study states. While authors further relayed a desire to replicate the results in a larger controlled study, this isn't the only research to conclude that blue-light-blocking lenses before bedtime can aid sleep.

A recent poster presentation from a Nova Southeastern University College of Optometry student demonstrated that blue-light-filtering lenses worn after 6 p.m. nightly for one week correlated with nearly doubled melatonin levels in subjects as compared to control.

Moreover, a meta-analysis from San Diego State University (SDSU)-published in October's Sleep Medicine-found more adolescents than ever are receiving insufficient sleep, a trend associated with longer daily device use. In fact, the study illustrated a 58 percent increase in the numbers of adolescents sleeping less than seven hours nightly, between 1991 and 2015. On top of that, researchers determined adolescents online more than five hours daily were likely not sleeping enough, as compared to peers who spent only an hour online daily.

"It's particularly important not to use screen devices right before bed, as they might interfere with falling asleep," notes the SDSU study author in a news release.

Access AOA's pediatric, blue-light resources

So, why does blue-light exposure before bedtime affect sleep? It's all about the body's "internal clock." Melatonin, a natural hormone that helps regulate the body's circadian rhythm, typically elevates in the evening hours to promote sleep; however, artificial blue light mimics natural sunlight, tricking the eyes into suppressing melatonin production. This suppression is believed to correlate with wakefulness and a delayed or disrupted sleep cycle.

"Although the light emitted by personal electronic devices is not bright enough to damage the human retina, it is able to stimulate blue-light-sensitive ganglion cell photoreceptors that regulate circadian rhythms," according to the Blue Light Impact in Children fact sheet from the AOA's Infant & Children's Vision Committee. "As a result, cellular telephone, tablet and personal computer use before bedtime can delay sleep onset, degrade sleep quality and impair alertness the following day."

Although emerging research suggests amber-tinted lenses could help reduce these sleep-altering effects, limiting device use before bedtime is recommended as the most effective method. So, too, limiting extended device use can have other benefits. Prolonged screen time can exacerbate dry eye symptoms, promote blurred vision and even headaches.

Doctors can access the fact sheet for more information on the blue-light debate, including references for further reading on the subject, and visit AOA Marketplace for the patient resource, "In the Dark on Blue Light" fact sheet.

Click here to read more about nutrition's role in combating blue light's ocular effects.

December 28, 2017

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