Melatonin

Helps regulate circadian rhythm and signals the body that it's time to sleep. Effective for jet lag — can help reset the body clock when traveling across time zones. May reduce the time it takes to fall asleep (sleep onset latency). Useful for delayed sleep phase disorder, especially in adolescents and young adults. May benefit shift workers who need to sleep during the day. Has antioxidant properties. May support eye health and reduce symptoms of tinnitus.

Start with the lowest effective dose: 0.5–1 mg taken 30–60 minutes before bedtime. If needed, may increase to 3–5 mg. Higher doses are not necessarily more effective — some research suggests lower doses (0.3–1 mg) work better for sleep. For jet lag: 0.5–5 mg at bedtime for several days, starting the day of arrival. Extended-release forms may help with staying asleep. Timing matters more than dose.

Tart cherries and tart cherry juice (richest food source), tomatoes, walnuts, grapes, rice, barley, oats, mushrooms, corn, asparagus, pomegranate, broccoli, cucumber. However, food sources provide much smaller amounts than supplements.

Common: Morning grogginess (especially at higher doses), headache, dizziness, daytime drowsiness, nausea, vivid dreams or nightmares. Less common: Short-term feelings of depression, mild anxiety, irritability, reduced alertness, confusion, low blood pressure. Most side effects are dose-dependent and resolve with lower doses.

Melatonin is a hormone, not a nutrient, so there is no traditional 'deficiency.' However, reduced melatonin production (common in aging, shift work, excessive evening light exposure) is associated with: difficulty falling asleep, disrupted sleep patterns, poor sleep quality, daytime fatigue, jet lag severity, and potentially increased oxidative stress.