Why do some people dream in black and white?

Studies from the 1940s and 1950s found that many people reported black-and-white dreams. By the 1960s and 1970s, as colour TV became standard, the proportion shifted: most people now report dreaming in colour. A 2008 study found that people over 55 who grew up with black-and-white media dreamed in greyscale about a quarter of the time, while younger people almost always dreamed in colour. It seems the brain draws on visual memories and media formats when constructing dream imagery. Some researchers also suggest that people may simply not remember colour in their dreams and default to greyscale when unsure.