Why You Should Watch Your Screen Time

This article was originally published in our Fall 2020 print issue.

Time spent on devices such as laptops and phones has increased significantly over the past few years. Especially as the recent pandemic has forced millions to exercise social distancing and spend more time at home, much of daily life has gone digital. In a recent study performed by a national parenting nonprofit, it was found that there was almost a 500% increase in online time for young children in the US. Even before the pandemic, it was noted in the study that “the typical American already spent nearly 11 hours per day in front of digital screens”. While the most important, and urgent concern at the moment is protecting oneself from the possibility of COVID infection, it is also important to consider what kinds of consequences can arise from using technological devices for more extended periods of time.

A major concern of more frequent phone and laptop use throughout the day is that people will continue overuse in the nighttime as well. Researchers studying light-emitting devices have found that these types of devices are generally made to emit a significant amount of short-wavelength light emissions, or blue-light, in order to enhance the device’s efficiency and brightness during the day. As a result, if one uses their device during the evening without any sort of modification, they are being exposed to a strong source of artificial light. A study centered around university students has found that this type of device use has significant health implications because blue-light exposure during the evenings has been found to alter sleep and circadian physiology. The study goes on to warn that evidence points to associations between blue-light exposure and adverse health symptoms such as insomnia and psychiatric problems.

Blue-light is able to affect the human sleep cycle by suppressing the levels of melatonin, a sleep-facilitating hormone, and can shift the body’s circadian clock to a later time. This is useful during the day when one would need to be alert and stay awake, which is why having sunlight exposure, which contains natural blue-light, can be beneficial. Evening-time blue-light exposure, on the other hand, will repress the amount of melatonin released. Dr. Allison Harvey, a UC Berkeley Professor of Clinical Psychology and Director of the Golden Bear Sleep and Mood Research Clinic, explains in her recent Berkeley Talks why light can influence the human circadian cycle: “light from the retina comes through to the suprachiasmatic nucleus, which is the seat of the circadian clock”. She goes on to explain that “the body itself is incredibly rhythmic”, which highlights that disrupting regular sleep times with blue-light exposure can influence and interrupt many of the body’s important functions and cycles. 

There are many temporary effects of having disrupted or insufficient sleep such as fatigue, irritability, or slower mental function, but there has been research studying the long-term health effects resulting from poor sleep quality over the years. Dr. Matthew Walker, a UC Berkeley Professor of Neuroscience and Psychology and the Director of the Center for Human Sleep Science, studies sleep and the related health effects in humans. In his interview on NPR, he notes that “there’s a strong relationship now between insufficient sleep and the mechanisms of Alzheimer’s disease”. This is because sleep allows the brain to “clear out all of the detritus [waste] that’s been building up, all of the metabolic waste that’s been building up throughout the day”.

In order to mitigate the effects of blue-light exposure on the quality of sleep, there has been research on the efficacy of blue-light blocking (BLB) technology. Items such as BLB glasses, which are made with an amber tint in order to reduce the emissions of blue-light to the eye, have become popular over the past few years as a simple solution. Many stores, both in person and online, have begun to offer options to purchase prescription glasses with blue-light filtered lenses, making them widely accessible. In order to analyze the efficacy of such a popular item, there have been studies looking at the glasses’ blocking potential. In the study analyzing light-emitting devices and the emission spectra across them, researchers found that orange-tinted glasses were able to significantly reduce the melatonin suppression that results from viewing an LED computer screen in the evening. The study also found that device applications that changed colors in the evenings to a more amber tone, similar to  “night-mode” or “dark-mode” on many devices, were also effective in reducing short wavelength emission. As a result, employing any of these BLB solutions appears to be an effective, convenient, and safe way to mitigate the effects of using devices closer to bedtime. 

The issue of blue-light exposure is an important public health matter because the very large majority of society comes into frequent contact with blue-light emitting devices. In an era where laptops and phones are integral parts of school and work life, it is incredibly difficult to simply stop using these devices. BLB technology serves as a strong solution for students and workers to begin mitigating the effects of blue-light on the quality of their sleep without sacrificing their device usage. It is crucial for everyone to consider establishing healthier evening time habits because, as previously explained by the professionals studying sleep and circadian science, establishing healthy and consistent sleep habits not only helps with school and work performance, but also invests in a healthier and happier future.