Actually, not true. Whether someone dreams in color or black and white depends actually on how perceptive they are when they wake...

It is possible to dream in either black and white or in color, but what really happens is when you wake up. Most people dream in color, but when people wake up, trying to recall a dream is a different story altogether, and what ends up happening is the memory of our dreams usually picks up the gray tones rather than the more vibrant tones. Ergo, it appears that you always dream in black and white. Your dreaming in color is probably what you usually do, and you're just more perceptive to it. The medication you're taking is probably in some way affecting your memory.

I for one have somewhat of a shitty memory, but I am highly imaginative and can remember stories or songs or ideas from years ago. Therefore, I never dream in black and white. And in fact, I don't think I have ever dreamt in black and white. And now I wonder if my memory is so good, if that could be a reason why I sometimes dream in cartoon. Hmm...