Does this indicate too much or too little light, or what?
Christmas Cactus With Reddish Leaves
Certified GKH Gardening Expert
Red leaves on a Christmas Cactus can indicate stress of some kind.
This could be due to bright light exposure or lack of nutrients in the soil.
It the plant root bound? This can cause the plant not to be able to take up nutrients.
Do you fertilize on a regular basis?
Here are some links to refresh you on the care requirements.