Vitamin B did it for me. If I eat later at night it definitely encourages this. A friend ate chocolate and had very vivid dreams but she only dreams in black and white. I dream only in color and I have noticed that things I have thought about before I go to bed seem to stimulate the severity. You can google orange juice, mustard, drugs, cheese, alcohol, herbs as well. lots of scientific research questioning this subject and interesting to realize how this relates to the brain.