Night settings

The sliders on the Night Settings tab are the heart of this program. Blueless applies these settings to the screen when:

Whenever these settings are active — in other words, whenever Blueless applies these settings to the screen — an orange dot appears next to the words ‘Night settings’ in the tab header.

How should you set these sliders? In order to minimize sleep disturbances and eye damage, I recommend:

You may also want to try reducing Gamma on the Advanced tab. This sometimes increases the legibility of text.

The reason for these recommendations is that blue light is the most energetic and therefore the most injurious to cells. It’s also the color that the nervous system mainly uses for setting its circadian rhythm. Green is the second-most energetic and may also have a slight effect on circadian rhythm. Red is low energy and probably harmless, and it probably has no effect on circadian rhythm.

The injurious effect and the circadian effect are unrelated. It’s a coincidence that blue light is the worst offender in both cases.

If you dislike the way colors look with blue completely removed, you can move the blue slider a little bit to the right. How much blue you remove is up to you. With this program you’re in charge. It will do some things automatically if you tell it to, but you can always take control.

If you remove some blue but not all, you can improve white balance by dimming red and green, because white balance on a computer screen is a function of the ratio of red, green, and blue.

But I urge you to try zero blue for a while. You may be surprised how easily you get used to it. You may find that after a while you forget that it looks odd. This happens because our brains have a powerful mechanism that adjusts to ambient light from which blue has been removed. This mechanism probably evolved over millions of years because our primate ancestors depended on color vision to find ripe fruit in foliage, and because natural light becomes reddish when the sun is near the horizon.

Anytime you need accurate colors — for example, when you want to watch a movie — you can restore the screen to normal by clicking Off at the top of the window. When you’re ready to reduce blue light again, click Night or Auto. You can also change colors temporarily by wiggling the sliders or by clicking Day at the top of the window.

This page was first published on April 4, 2019 and last revised on April 4, 2019.