Are Blue Light Filters Effective? A Closer Look at Sleep and Eye Health
Blue light filters and lighting systems designed to emit less blue light have seen a significant surge in popularity within the electronics industry over the past few years. Supported by multiple scientific studies suggesting that blue light can influence the sleep-wake cycle, many hardware manufacturers have modified their devices to reduce the blue light component during nighttime hours.
This development extends to e-readers as well, with various models from Tolino, PocketBook, and Kindle now featuring options that reduce blue light emission. According to our tests, there is currently no conclusive evidence indicating that the nightlight function on e-readers actually provides measurable health benefits. At the same time, I have personally had positive experiences with reduced blue light, which leads me to give this feature a favorable review. But is this praise truly justified?
Is Blue Light Relaxing?
A recent study that was widely discussed last week suggested that blue light filters may not be as effective in preventing disruptions to the sleep-wake cycle as previously believed.
The basis for this investigation was the observation that the blue light component in natural lighting actually increases visibly at sunset. Therefore, this should not result in people becoming more alert. So far, this seems logical.
Two key findings from the study are particularly noteworthy: First, at high brightness levels, any color of light can be stimulating, and second, when brightness is low, blue light is in fact more calming than warmer-colored light.
This is at least the case for mice, as the experiments conducted in the study involved these animals.
This highlights the main challenge in interpreting such data. While mice are often used in research to predict possible effects on humans, these results are by no means always directly transferable to people.
Are Results Transferrable to Humans?
This may represent one such instance, since mice are nocturnal creatures.
This raises the question of whether the influence of the day-night cycle on sleep patterns can be meaningfully compared between mice and humans. In their natural environment, mice are generally active at times of day that differ from human activity patterns.
I find it surprising that this aspect is not discussed anywhere. Several media outlets have even gone so far as to declare blue light reduction useless, based on this study alone.
Other research on sleep cycles, as well as studies investigating additional effects of blue light, also highlight other adverse effects caused by blue light. Therefore, the impact on the sleep cycle is not the sole relevant factor when it comes to reducing blue light; eye health is also a significant consideration.
For this reason, I recommend exercising a certain degree of caution before making definitive judgments.
In other words, since there is still no consensus, it is best to trust your own sense of well-being when deciding whether to reduce blue light exposure. This is particularly simple to test with smartphones and their built-in functions or apps.
Recommendation: Lower Brightness
Whether or not you choose to use an e-reader with a blue light reduction function, there is at least one lesson to take from this and other studies: screen brightness plays a significant role in influencing the sleep-wake cycle. I have already emphasized this point in our other article on the subject.
So, if you are reading on your e-reader in the evening or at night, it is certainly wise to gradually reduce the brightness as it gets later. The text should remain easy to read, but the light intensity should be kept as low as possible.
Since your eyes need some time to adapt to a dimmer screen, it is worthwhile to experiment a little in order to determine which setting is best suited to your personal preferences. Some e-readers provide various options for automating these adjustments (such as Kindle and PocketBook).
