We’ve all heard that screen time before bed is bad for sleep. If you have trouble falling asleep in the evening, as I almost always do, you’ve probably been told to turn off your phone and avoid watching TV for at least an hour or two before bed. There are two main reasons we hear this more in the last 20 years or so than we used to. The most obvious is the advent of smartphones, which blast our eyes with light from just a few inches away and which follow many of us to bed. Previous generations of technology simply weren’t in our faces with the same frequency from morning to night. But the focus on blue light in particular also began about 20 years ago, when scientists discovered that there was a type of photoreceptor in the eye that detects light specifically “for circadian responses rather than visual responses,” according to Stuart Peirson of the University of Oxford’s Sleep and Circadian Neuroscience Facility (SCNi). In an interview with The Guardianhe explained that these light-sensitive responses include “the setting of the circadian clock, the regulation of sleep and wakefulness, and also things like hormone responses like melatonin.” Blue light, it seems, affects these rhythms more than other parts of the light spectrum. Unfortunately for us, LED-based devices like phones, tablets, laptops, and even regular LED light bulbs emit more blue light than the incandescent bulbs of the 20th century, and that may be one reason why more people seem to suffer from poor sleep hygiene and related health problems. A large study published in The Lancet Psychiatry examined data from over 90,000 middle-aged adults and found that people with sleep problems were more likely to suffer from mental illnesses like depression and bipolar disorder.

Blue light is not a bad thing. Changes occur particularly in the blue part of the spectrum at dawn and dusk, and our bodies have evolved to sense these changes because they are important for setting our clocks. We have subsequently invented devices that emit light, filled our environments with it, and made them addictive. If you go to bed at night and stare at your bedside lamp for 10 minutes, your clock will (also) be set, only no one does it.

— Stuart Peirson from the Institute of Sleep and Circadian Neuroscience (SCNi) at the University of Oxford

OLED TVs for better sleep?

But there may be good news for those of us who like to watch TV before bed. A new study from OLED panel maker LG Display suggests that OLED screens are less harmful than their liquid crystal counterparts. Unlike LCD screens with LED backlights, OLED sets are self-luminous, meaning each pixel produces its own light. And the quality of that light appears to be better for sleep. The study found that LG Display’s OLED TV panels actually help viewers maintain healthy sleep patterns, and the company now boasts that its TVs are proven to be “sleep-friendly,” supporting eye health and overall well-being. The clinical trial examined the effects of TV panels on sleep in collaboration with researchers at Kookmin University in Seoul, South Korea. It’s worth noting that this was a relatively small-scale study, following 40 adults over a two-week period. During the study, test subjects were divided into groups that watched the same content on either LCD or OLED TVs. The researchers measured levels of the sleep-promoting hormone melatonin in men and women throughout the test period.

According to the resulting report, melatonin secretion in the LCD TV group decreased by an average of 2.7% after two hours of watching TV. This seems to confirm what scientists have warned about regarding blue light exposure and its potential impact on circadian rhythms. But surprisingly, melatonin secretion in the OLED TV group actually increased by an average of 8.1% after subjects watched identical content for the same period of time. The report explains that the human body needs melatonin to wake up in the evening and prepare for sleep, and that sleep disturbances can result when melatonin secretion is disrupted. According to LG Display, modern LCD panels emit 70-80% blue light because they rely on strong LED backlighting on a continuous basis. LG Display’s self-emitting OLED TV panels emit only 36% blue light, according to the report.

OLED TVs not only minimize the negative effects on melatonin secretion while watching TV, but also effectively contribute to a healthy sleep pattern of viewers by increasing the activation of the parasympathetic nerves responsible for well-being.

— Professor Kim Chang-wook, head of a research team at Kookmin University

Eyesafe certification for TVs?

While I don’t question the results of this study, I tend to take studies sponsored by interested companies with a grain of salt. But these results confirm previous findings that LG Display’s OLED panels support eye and body health in ways that LCD screens can’t. In 2023, LG Display’s OLED TV and monitor panels were the first in the industry to be certified “Circadian Friendly” by TÜV Rheinland, a Germany-based testing, inspection and certification organization that tests engineering systems and products around the world. LG Display’s OLED TV panels are used not only in LG-branded TVs, but also in some TVs from Sony and Samsung (sold in the U.S.) and Panasonic and Philips (sold in Europe). These panels are said to have the lowest blue light emission of any existing TV panel and lack the screen flickering found in some competing technologies – a phenomenon that LG Display says can potentially lead to vision loss. Due to these characteristics, LG Display’s OLED panels received the “Eyesafe” certification, developed by US-based Eyesafe in collaboration with TÜV Rheinland. Eyesafe is a provider of advanced blue light mitigation technologies, solutions and standards. To meet the requirements for Eyesafe certification, a product must have blue light emission and color performance that meets the international standards and guidelines of the American National Standards Institute (ANSI) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP). In addition to the Eyesafe certification, LG Display’s OLED panels have been certified as “flicker-free” and “anti-glare” by independent global safety research company UL (Underwriters Laboratories). In fact, one of the reasons I bought the Sony OLED TV I currently use was because I found it more pleasant to watch than LCD TVs. Of course, I appreciate the deep blacks and lack of blooming, but I also find that OLED TVs offer a pleasant visual experience that reminds me of the best plasma and tube TVs of the past.

We will introduce products and technologies that offer differentiated customer value based on OLED panels that are safe for the human body while providing the best image quality.

— Soo-young Yoon, CTO and Executive Vice President at LG Display

As much as I’d love to tell you that switching to an OLED TV will cure your insomnia, that’s probably not the case. (It didn’t work for me, anyway.) And the results of LG’s study need to be considered in the context of the overall factors that affect sleep, including things like exercise, stress, your sleep environment, and the times you go to bed at night and wake up each day. I’ve seen studies suggesting that spending 20 minutes outside every day can improve your sleep more than limiting screen time in the evening. The same goes for keeping your sleep environment dark, cool, and quiet, getting regular exercise, and sticking to a regular sleep schedule, even on weekends. It’s likely that multiple factors contribute to a person’s overall sleep quality, and that can have a significant impact on overall health. If OLED panels do indeed contribute to better sleep health, I may finally have an excuse to replace my old iPhone and upgrade to a newer model, most of which use OLED displays these days. Will sleep quality play a role in your next TV or gadget purchase? Share your thoughts in the relevant forum thread below.