or do what I do. I only do serious work in photoshop and lightroom on photos in dark room, with very dim, indirect light if any light at all.
It also helps me extend the working life on my CRT because i only drive it at 95-100 cd/m^2. If the room was brigher i'd have to set it to be brighter with a higher measured luminance value, which shortens the life of the CRT as a color accurate, profileable monitor.