Melatonin: What It Is, What It Isn’t, and Why You’re Probably Taking Too Much

Melatonin sales in the United States exceed $900 million annually. It is sold in doses of 5mg, 10mg, and sometimes higher — right next to the vitamins, with packaging that implies it will knock you out. Here is what melatonin actually is, and why most of that is wrong.

What Melatonin Actually Does

Melatonin is a timing signal, not a sedative. It is produced by the pineal gland in response to darkness and tells your brain that it is night — that the biological processes associated with sleep should begin. It does not cause sleep directly. It shifts the window in which sleep is possible.

Think of it like a starting gun. It announces that the race should begin. It does not run the race. If your circadian rhythm is well-calibrated to your schedule, your body is already producing sufficient melatonin at the right time, and taking additional melatonin won’t change much. If your rhythm is shifted — jet lag, shift work, difficulty falling asleep early enough — melatonin taken at the right time can help shift your clock. That’s its legitimate use case.

The Research on Dosing

The effective dose for melatonin’s circadian-shifting effect is 0.5mg to 1mg, taken 30–60 minutes before your target sleep time. Higher doses (3mg, 5mg, 10mg) do not produce proportionally better results — they primarily produce a longer duration of elevated melatonin levels, which can cause grogginess the following morning (“melatonin hangover”). The doses sold in American pharmacies are typically 5–10x the physiologically effective amount.

Brzezinski A et al. Effects of exogenous melatonin on sleep. Sleep Medicine Reviews. 2005.

When It Works

Jet lag: Melatonin taken at the local bedtime of your destination helps shift your circadian clock to the new time zone. This is its most evidence-supported application. Dose: 0.5–1mg.

Shift work: People whose work schedules require sleeping at non-standard times can use melatonin to shift their sleep window. This requires careful timing and consistency.

Delayed sleep phase: People who naturally want to sleep at 2am and wake at 10am — a genuine chronotype called “delayed sleep phase syndrome” — can use low-dose melatonin taken earlier in the evening to gradually shift their window earlier.

When It Doesn’t Work

As a sedative for general insomnia: If you can’t sleep because you’re anxious, uncomfortable, too hot, or your circadian rhythm is simply healthy but your schedule doesn’t cooperate — melatonin won’t help significantly. You’re not deficient in the timing signal; the underlying problem is elsewhere.

At high doses: Taking 10mg of melatonin does not make you 10x more likely to sleep. It makes you more likely to wake up groggy and to experience disrupted sleep cycles from artificially elevated hormone levels at times they shouldn’t be elevated.

“Melatonin is a clock adjustment tool, not a sleeping pill. Using it as a sleeping pill is like setting your watch to make it earlier.”

What to Try Instead

If you’re taking melatonin because you can’t fall asleep, the more useful interventions are environmental: lower the room temperature to 65–68°F, eliminate all light from the bedroom, put the phone in another room, and switch from synthetic to natural fiber bedding. These address the actual variables that prevent sleep onset. They’re less convenient to take than a gummy. They’re more effective.