Is there a Night Reading Mode toggle (black background, white text)?
The white color background of computer screens actually contains a lot of blue light, which degrades & inhibits the formation of melatonin, which is required for sleep. Therefore evening computer use should use "inverse" illumination, with the text being colored and the screen background dark.
So is there a way to simply toggle such a mode? If not, why not?
Alla svar (1)
Wouldn't that be done better as a global switch, applied by the OS rather than in separate applications? Maybe you should be arguing this with Microsoft, Apple or display hardware manufacturers.
My admittedly brief read-up on this topic (I'm always wary of what might be pseudo science) suggests that removal of blue light is more relevant than inverting the colours.
For myself, I have sight issues that make reading white characters on a black ground somewhat tiring, so I'd be looking for a dimming rather than an inversion.
You could of course, in Thunderbird, choose a theme that offered a dark background and set a suitable colour for the characters.
Bear in mind that a traditional LCD backlit screen will still be generating a broad spectrum of light, so there will still be a blue component, only somewhat attenuated.