The bottom line first
10mg melatonin creates pharmacological supraphysiological levels that blunt receptor sensitivity. The effective dose is 0.3–1mg.
Endogenous melatonin peaks at approximately 100–200 pg/mL in healthy adults. A 0.5mg oral dose, accounting for first-pass hepatic metabolism (~80% loss), delivers a serum level of roughly 100–300 pg/mL — within physiological range. A 10mg dose produces levels 10–50× higher, which does not improve sleep proportionally and may downregulate MT1 and MT2 receptor sensitivity over time.
The reason Indian products are 5–10mg is regulatory habit and commercial convention — not evidence. The effective dose range is 0.3–1mg for most adults. Anything above 3mg is a pharmacological intervention, not a supplement dose.
How melatonin works: the receptor and pathway detail
Melatonin (N-acetyl-5-methoxytryptamine) is synthesised from serotonin in the pineal gland in a light-dependent process regulated by the suprachiasmatic nucleus (SCN) — the brain's master circadian clock. Secretion begins 1–2 hours before habitual sleep onset (the "dim-light melatonin onset" or DLMO) and peaks at 2–4am before suppression by morning light exposure.1
Melatonin acts on two primary G-protein-coupled receptors: MT1, which mediates acute inhibition of SCN neuronal firing (the sleep-onset signal), and MT2, which mediates circadian phase-shifting. Exogenous melatonin mimics the DLMO signal — it doesn't sedate you, it tells your SCN that it's nighttime. This is why melatonin is more accurately called a chronobiotic than a hypnotic. It shifts timing, not depth, of sleep.2
The dose–response curve for MT1 and MT2 activation is not linear. Receptor saturation occurs at physiological concentrations (~300 pg/mL). Above this, additional melatonin does not proportionally increase receptor activation. Supraphysiological doses show evidence of receptor downregulation with chronic use — meaning the sleep-promoting signal becomes weaker over time, not stronger.3
What the dose evidence actually shows
A landmark dose-finding study by Dollins et al. (1994) compared 0.1mg, 0.3mg, 1mg, and 10mg melatonin in healthy adults. All doses reduced sleep onset latency. There was no significant additional sleep benefit from doses above 0.3–1mg. The 10mg dose produced significantly elevated next-morning fatigue and reduced alertness — the hangover effect.4
A 2022 meta-analysis of 19 RCTs by Ferracioli-Oda et al. found that melatonin reduced sleep onset latency by 7.06 minutes (95% CI: 4.37–9.75) versus placebo — a real but modest effect. Crucially, this effect was present at doses as low as 0.3mg and did not increase significantly at higher doses. Total sleep time improved by 8.25 minutes (95% CI: 1.74–14.75). The evidence base is weighted toward sleep-onset delay (circadian mismatch) rather than primary insomnia.5
The India-specific problem
Melatonin in India occupies a regulatory grey zone. It is not listed as a prescription-only drug under the Drugs and Cosmetics Act, yet it is not licensed as a nutraceutical under FSSAI's functional food framework either. This ambiguity means it is sold without standardised dosing guidance, and manufacturers have defaulted to high doses that make the product "feel" more powerful — a classic supplement-marketing pattern.
Most Indian adults presenting with sleep complaints are not suffering from circadian phase disorders — they are suffering from hyperarousal, anxiety, and poor sleep hygiene in the context of urban Indian work culture (late office hours, blue-light exposure, commute fatigue, and financial stress). For hyperarousal insomnia, melatonin is weakly effective regardless of dose. The appropriate interventions are CBT-I, magnesium glycinate, and addressing the arousal source.6
Melatonin earns its strongest evidence for: (1) jet lag — take 0.5mg at the target destination's bedtime on the day of travel; (2) shift work — take 0.5–1mg before planned daytime sleep; (3) delayed sleep phase syndrome (DSPS) — consistent late sleep onset pattern, take 0.5mg 5–6 hours before habitual sleep onset. For garden-variety difficulty falling asleep from stress and screen time, address the root cause first.
Products on the Indian market
| Product | Dose | Form | Price / 30d | Verdict |
|---|---|---|---|---|
| Lunasom 0.3mg (Carbamide Forte) | 0.3mg | Tablet | ₹349 | Recommended |
| Wellbeing Nutrition Sleep 1mg | 1mg (melts) | Oral strip | ₹499 | Recommended |
| Himalayan Organics Melatonin 3mg | 3mg | Tablet | ₹399 | Acceptable |
| GNC Melatonin 5mg | 5mg | Tablet | ₹699 | Overdosed |
| MuscleBlaze Melatonin 10mg | 10mg | Tablet | ₹599 | Avoid |
| Most pharmacy-brand "Melatonin" | 5–10mg | Tablet | ₹200–400 | Avoid |
Timing matters as much as dose
Melatonin must be taken relative to your DLMO, not relative to clock time. For most adults with a regular schedule, taking 0.5mg 30–60 minutes before desired sleep onset works well. For jet lag westward (e.g., India to London), take 0.5mg at the destination's bedtime on the day of arrival and for 2–3 days following. For jet lag eastward (London to India), take 0.5mg at the destination's local midnight for 3–4 days.7
If you want to try melatonin for sleep: buy the lowest dose available (ideally 0.3–0.5mg; Carbamide Forte Lunasom or equivalent). Take 30–60 minutes before your target bedtime. Eliminate screen light (or use blue-light blocking glasses) from 9pm. Give it 7 nights before assessing. If 0.5mg does nothing after a week, you likely have a hyperarousal problem, not a phase problem — and melatonin won't fix it regardless of dose.
Safety and dependency concerns
At physiological doses (0.3–1mg), melatonin has an excellent safety profile. It is not chemically habit-forming in the way that benzodiazepines or Z-drugs are — there is no physical dependence or withdrawal syndrome documented at low doses. However, chronic high-dose use may blunt endogenous melatonin production via feedback inhibition on the pineal gland, though evidence in humans is not conclusive.8
Melatonin is contraindicated in pregnancy (animal data showing interference with reproductive hormones), in autoimmune disease (it modulates immune function), and should be used with caution alongside anticoagulants (warfarin interaction documented) and immunosuppressants. In children, it is used clinically for ASD-associated sleep disorders but should be physician-supervised; dose thresholds in paediatric use are much lower than adult supplemental doses.
References
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