Melatonin

Melatonin signals biological night; it does not induce sleep the way a hypnotic does. Evidence supports 0.3–1 mg taken 2–4 hours before target bedtime for jet lag and delayed sleep phase, while the 5–10 mg doses common in retail products often cause grogginess without added benefit. It is not a fix for poor sleep hygiene, and long-term high-dose use in adolescents lacks safety data. Light exposure timing outperforms melatonin for most circadian problems.