The low blue light mode on a desktop monitor is a color temperature setting. It is activated from the monitor’s built-in menu. Its name varies between manufacturers: blue light filter, blue light reduction, low blue light mode. English-language menus refer to low blue light or low blue mode for the same family of function.
As for its effectiveness, there is a dated and publicly available French source. It is the press dossier published by Anses on May 14, 2019, concerning the health effects of LED systems. In it, the agency states that, for monitors claiming to limit blue light emission, “no actual effectiveness was observed.”
It does, however, identify two measures that do work. Reducing the color temperature, in other words switching to a warmer white, and reducing brightness have “shown some effectiveness in reducing the amount of blue in the spectrum.”
This provides a criterion that can be checked within seconds on your own monitor. Switching to a warmer white is visible: the image takes on a yellowish tint. A setting that does not alter the displayed hue therefore does not alter the color temperature.
Where to find the setting and what it changes in the image
The setting can be found in the monitor’s built-in menu, which opens using the buttons or joystick located behind the panel. It is most often found under a visual comfort section, sometimes with several intensity levels. The selection remains stored in the monitor and therefore applies to any machine subsequently connected to it.
What it changes is the distribution of primary colors in the displayed image, and therefore the color temperature, expressed in kelvins. The lower this value, the warmer and less blue the emitted light is said to be. A 2,700 K source produces warm light, while a 6,500 K source produces cool light.
The measurements cited by the agency place monitors toward the upper end of this scale. The document describes them as “particularly rich in blue,” between 4,100 and 7,000 K. This applies to televisions, computers, mobile phones and tablets. Hence the visible effect of the mode: it shifts a monitor set to a cool temperature toward warmer tones, and the white of a page takes on a cream tint.
Product specifications use several names for this function, which explains why it can be difficult to search for. The 28-inch IPS 4K UHD White Office Monitor lists “Visual comfort: blue light filter and anti-flicker technology.” The 28.2-inch IPS 4K UHD+ Office Monitor advertises “blue light reduction.” The 34-inch IPS UWQHD White Curved Monitor features a “low blue light mode.”
These terms refer to the same family of function, on monitors that offer it, such as the 28-inch IPS 4K UHD White Desktop Monitor. Other workstation settings are covered in our article on what you should be able to adjust on a monitor.
Hardware or software solution: the difference that matters
Two distinct technologies are marketed under the same name. TÜV Rheinland, the certification body that awards the Low Blue Light label, describes them separately on its page dedicated to this certification.
The software-based approach reduces the output of blue pixels. The process is straightforward. It creates a pronounced yellow tint and degrades color rendering. This is the principle behind night modes built into operating systems.
The hardware-based approach acts on the backlight. It works through a modification of the luminescent material or targeted filtering. It targets the 415 to 460 nanometer range without altering color rendering in the same way. The function is then integrated into the panel, whose operation is described in our article on monitor panel technologies.
A software mode modifies what the computer sends, while a hardware mode modifies what the panel emits. Certified products can be checked in the organization’s database, making it possible to verify a claim rather than simply take it at face value.
What the mode changes, and what it does not change
This press dossier reports on an expert assessment based on more than 600 scientific publications and a measurement campaign covering protective products sold to the general public.
The agency confirms the toxicity of blue light to the retina. It identifies disruptions to biological rhythms and sleep when exposure occurs in the evening or at night, particularly in children, and concludes that exposure before bedtime to LED monitors enriched in blue light can negatively affect sleep duration and quality. The time of day therefore matters more than the number of hours spent in front of the monitor.
Regarding protective products sold to the general public—filters, treated lenses and glasses—the agency considers their effectiveness to vary considerably depending on the device. None has been demonstrated to provide protection against long-term exposure or delayed sleep onset. Specialized glasses filter more blue light than treated ophthalmic lenses, but neither is considered sufficient as personal protective equipment.
For monitors claiming to limit their blue light emission, the agency observed no actual effectiveness. The criterion left to the reader is visual: a mode that leaves the image unchanged has not altered the color temperature.
Operating system night modes fall under the software-based approach described above, with the same caveat concerning the melanopic band—the one involved in circadian rhythms—where filtering capacity varies considerably from one device to another. The document’s most direct recommendation concerns no equipment at all: limit exposure to blue-rich light before bedtime and during the night.
The two settings that have shown an effect
Two settings are available in the menu of every desktop monitor, without requiring any special function or additional software. They are the two identified by Anses. They have shown some effectiveness in reducing the amount of blue in the spectrum.
Color temperature can be adjusted by choosing between presets named cool, standard and warm, or sometimes by setting a value in kelvins. Switching to a warmer setting is immediately visible in the white areas of the monitor. Fine adjustment is explained in our article on adjusting monitor colors.
Brightness should be adjusted according to the lighting in the room, rather than in absolute terms. A monitor set to maximum brightness in a dimly lit room emits far more light than necessary for comfortable readability. Lowering this level reduces the amount of light emitted, and therefore the amount of blue light it contains.
These two settings have one advantage over any dedicated function: their effect can be seen immediately, with the naked eye. The appropriate level is a matter of comfort. A neutral image is suitable for color-related work, while a warmer image may be more comfortable at the end of the day. There is no need to keep the same level from morning to evening, since the setting can be changed with two presses in the menu.
