Noni, Morinda citrifolia, stimulates the hormones serotonin and melatonin. Serotonin affects mood, emotions, and sleep; an imbalance in levels of serotonin may contribute to depression. Melatonin regulates the Circadian rhythm, which helps you sleep; keeping this regular will help get a good night's rest, also improving your mood. Noni is promoted as a dietary supplement to prevent cancer, prevent infections, treat high blood pressure, and help with other conditions.