At this point, most people who have responded are convinced of a link between melatonin and increased "vividness" (88% of respondents) and frequency of dreams (63% of respondents), as well as improved dream recall (56% of respondents). I have a couple of hypotheses, and I encourage others to look into them if they find them promising. 1. Melatonin might be a dream-inducing (oneirogenic) substance. I have heard that melatonin breaks down into 5-Methoxy-Dimethyltryptamine, which could be responsible for the intense visual stimulation. I would appreciate any verification of this claim. 2. Melatonin might stimulate REM sleep. In the popular book "The Melatonin Miracle" (Pierpaoli, Regelson, & Colman), the authors write: During the time of peak melatonin production, we are more apt to experience REM sleep... (paperback edition, p. 213) 3. Melatonin, by stabilizing out-of-kilter sleep rhythms, might allow persons to get "back in synch" with their natural dreaming cycles. If this is so, perhaps people who are REM deprived begin dreaming more, therefore remembering more frequent and vivid dreams.