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Why You're Probably Taking Too Much Melatonin (And What to Take Instead)

Walk into any pharmacy and the melatonin options typically start at 5mg, with many products offering 10mg tablets. But here is what the label does not tell you: your body naturally produces roughly 0.1–0.3mg of melatonin per night. That 10mg tablet is up to 100 times more than your pineal gland would ever release.

Does that matter? According to MIT researchers who pioneered melatonin supplementation research — yes, significantly. Here is what the science actually says about dosing, timing, and when melatonin is not the right tool at all.

The MIT Research That Changed the Conversation

In the 1990s, Professor Richard Wurtman's team at MIT conducted a series of studies that established the dose-response relationship for supplemental melatonin. Their findings were striking: doses of 0.3–0.5mg were as effective as 3–10mg for shortening sleep onset time — but with dramatically fewer side effects and no next-day grogginess.

The reason is straightforward. Melatonin works as a signal, not a sedative. It tells your brain that it is nighttime. Once receptors are saturated — which research suggests happens well below 1mg — additional melatonin provides no additional benefit, but remains in your system long enough to cause morning drowsiness and potential hormone disruption.

What High-Dose Melatonin Does to Your Body

1. Suppresses natural production

Taking high doses of exogenous melatonin may suppress your pineal gland's own production over time. Your body can downregulate its own output when it detects consistently high levels from an external source — similar to the mechanism seen with testosterone supplementation.

2. Morning grogginess (melatonin hangover)

Melatonin has a half-life of 40–60 minutes, but its metabolites remain active longer. A 10mg dose taken at 10pm may still be exerting sedative effects at 6am. This is why many people report feeling foggy even after a full night of sleep on high-dose melatonin.

3. Hormonal interference

Melatonin interacts with reproductive hormones. Some research suggests long-term use of high doses may affect LH and FSH levels. This is particularly relevant for adolescents and people trying to conceive — though evidence is not yet conclusive in humans.

The Right Dose: What Research Supports

• Sleep onset (healthy adults): 0.5mg taken 30–60 minutes before bed
• Jet lag: 0.5–3mg at destination bedtime for 2–4 days
• Shift work: 1–3mg at intended sleep time
• Children: consult a paediatrician; lower doses (0.5–1mg) if used at all

When Melatonin Is Not the Right Tool

Melatonin addresses one specific problem: poor circadian timing. If you struggle to fall asleep because your body clock is delayed, melatonin can help reset the timing. But it may not help if your sleep problems are caused by:

• High cortisol and anxiety at bedtime — which requires a different approach
• Magnesium deficiency — associated with reduced sleep quality and increased night wakings
• Sleep apnoea or other structural airway issues
• Poor sleep hygiene (blue light exposure, irregular schedule)

For cortisol and anxiety-driven sleep issues, adaptogens like KSM-66 ashwagandha and L-Theanine have stronger clinical support. These are covered in our sleep supplements evidence ranking.

Practical Takeaway

If you currently take 5–10mg of melatonin and still feel groggy in the mornings, the dose is almost certainly the problem — not insufficient sleep. Try cutting to 0.5–1mg and giving it two weeks. Most people find equal or better results at a fraction of the dose, with none of the morning fog.

If reducing the dose does not help, it is worth reconsidering whether melatonin is addressing the actual cause of your sleep problems — or just treating a symptom of something else.

⚕️ Disclaimer: This article is for informational and educational purposes only. It does not constitute medical advice. Supplement dosing recommendations are based on available research and may not apply to everyone. Consult a qualified healthcare professional before starting any supplement, especially if you are pregnant, nursing, or taking medications.