Hi, Is your chameleon new? darker colors can mean he's stressed out. The ambient temperature of your cage should be about 75-80, while his basking spot should be 90-95 degrees (males) the basking spot for a female should be 85 degrees. Is his cage in a high traffic location? next to doors, windows, places where people walk by, air vents. Move him to a spot where there wont be so much activity. Make sure there is lots of foliage to hide in.