Melatonin, the body's darkness hormone, is sold as an inexpensive supplement, or by prescription in some countries, for sleep and body-clock timing. It reliably helps reset the body clock after long flights and late-running sleep schedules, and helps people fall asleep slightly faster. Claims that it slows aging rest only on animal and laboratory work. Main risks are next-morning drowsiness and worse blood sugar handling when it overlaps meals. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Fasting glucose | 70–99 mg/dL | Safety check: melatonin can impair glucose handling |
| HbA1c | 4.0–5.6% | Safety check for longer-term glucose effects |
| Blood pressure | Below 120/80 mmHg | Expected small decrease; safety check with nifedipine |
| LDL cholesterol | Below 100 mg/dL | Expected small decrease |
| INR (warfarin users only) | No established target; change from own stable INR | Safety check: case reports of altered clotting control |
| Femoral neck bone mineral density | No established target; change from own baseline | Expected increase |
Cadence: Baseline before starting; 2 weeks (INR and blood pressure where relevant); 3 months (fasting glucose, HbA1c, blood pressure and lipids); then every 6–12 months; bone density scan repeated after one year