Melatonin is the body's night signal, not a sedative. It shortens time to fall asleep by minutes and realigns the body clock after travel or shift changes. Slow-release forms lower night-time blood pressure; doses before surgery calm nerves and reduce confusion afterwards. Harms are mostly mild and reverse on stopping. Products often contain far more or less than the label. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Fasting glucose | 75–85 mg/dL | Melatonin suppresses insulin release |
| HbA1c | 4.8–5.2% | Detects cumulative glycaemic drift from nightly use |
| Nocturnal systolic blood pressure | Falls 10–20% below daytime mean | Non-dipping is the pattern melatonin corrects |
| Sleep onset latency | Under 20 minutes | The primary outcome melatonin is taken for |
| Gamma-glutamyltransferase | Under 25 U/L in men, under 20 U/L in women | Tracks the hepatic benefit in fatty liver disease |
| International normalized ratio | Within the individual's prescribed target band | Case reports describe drift after starting melatonin |
| Morning alertness on a validated sleepiness scale | Score under 10 on the Epworth Sleepiness Scale | Detects next-day carry-over, the commonest harm |
| Overnight urinary 6-sulfatoxymelatonin | No established target exists; track the change from the individual's own pre-treatment baseline instead | Estimates the body's own night-time output |
Cadence: Baseline set before starting; ambulatory blood pressure and, for warfarin users, the international normalized ratio rechecked at four weeks; fasting glucose and HbA1c repeated at three months, then every six to twelve months for continuous users; liver enzymes repeated at twelve weeks only where a hepatic indication prompted use. Qualitative markers are typically logged nightly for the first month.