The thing that tires your eyes is usually not the brightness of the screen. It is the difference between the screen and whatever is behind it.
Fix the wall before the desk
A bright screen against a dark wall forces your eyes to adapt every time you look up. Putting a modest amount of light on the wall behind the monitor reduces that jump. This is called bias lighting, and it is the cheapest change with the most noticeable effect.
It does not need to be bright. If the glow is obvious as a light source, it is too strong — you want the wall lifted out of blackness, not lit.
Then the desk, from the side
A task lamp belongs beside the screen, not behind you. A light behind you reflects straight off the panel into your eyes, and a light directly above a glossy screen does the same. Side lighting puts illumination on your hands, keyboard and paper without landing on the display.
Monitor light bars, and when they are worth it
A bar that clips to the top of the monitor throws light forward onto the desk and, by design, not onto the screen. That solves glare properly in a small space. It is the right answer when there is no room for a lamp and the wall is too far away to light.
Color temperature matters less than people say, except at night
Through the day, match roughly what is coming through the window so the room does not feel split. In the evening, warmer light is more comfortable — not because of any health claim we are qualified to make, but because a cold, bright desk in a dark house is simply unpleasant to sit at.
Avoid
Color-cycling light behind a monitor looks striking in a photograph and is distracting in use. If you want color, set it once and leave it. A strip that animates in your peripheral vision for eight hours is a tax on attention.