How Much Melatonin Is Too Much? Safe Dosage, Side-Effects & Overdose Symptoms
What Your Body Actually Produces (Natural Melatonin Levels)
The human brain secretes about 0.3 mg of melatonin per night under normal conditions1 That’s the baseline “sleep signal.”
Yet most over-the-counter supplements start at 3 mg and go to 10 mg+2—ten to thirty times the physiologic amount.
Melatonin Side-Effects: What Happens When You Take Too Much
At low doses (0.1–1 mg), melatonin can help sleep onset with minimal side-effects3. As the dose increases, risks increase:
- Daytime drowsiness / grogginess
- Headaches, dizziness
- Nausea or digestive upset
- Vivid dreams or nightmares
- Irritability or mood changes
- Older adults: confusion/balance issues → fall risk4
The High-Dose Trap (More ≠ Better)
One clinical trial in older adults found 0.3 mg restored natural levels, while 3 mg caused next-day drowsiness4. High doses may also fragment REM sleep3.
Are High Doses Ever Justified?
Pharmacology studies tested 50–100 mg to map safety margins5. Tolerated under supervision, yes—but no meaningful sleep benefit and far more side-effects6. For healthy adults, ≥5 mg is rarely necessary.
Quality & Label Accuracy Matter
A JCSM analysis found >70% of melatonin products deviated ±10% from the label; some were nearly 4× higher7. You might think you’re taking 3 mg, but actually ingest more.
Melatonin Dosage Guide (Adults): How Much Should I Take?
0.3–1 mg typically helps sleep onset; 1–3 mg can be used short-term for jet lag. Reserve 5 mg+ for clinician-guided cases.
Limit screens 30–60 minutes before bed and dim lights. Behavior beats “dose chasing” for most people.
Prefer accurately dosed, third-party tested, low-dose melatonin combined with calming botanicals.
Melatonin FAQ: Safety, Timing, Overdose Symptoms
Is melatonin safe?
Generally safe short-term for healthy adults at low doses, but higher doses increase side-effects and may disrupt REM. Talk to your clinician if you have medical conditions or take other meds.
When should I take melatonin?
Usually 30–60 minutes before bed for sleep onset. For jet lag or circadian issues, timing depends on your travel direction/schedule—follow a clinician’s plan.
What are melatonin overdose symptoms?
Excess dosing can cause pronounced drowsiness, headaches, nausea, dizziness, confusion (especially in older adults), and sleep architecture disruption. Seek medical advice for concerning symptoms.
Conclusion
Low-dose melatonin works best for most adults. Your body makes ~0.3 mg; jumping to 5–10 mg often adds side-effects without better sleep. Start low, protect your routine, and choose accurate products.
Related: Melatonin Side-Effects: What to Expect & How to Avoid Them • Insomnia Guide: Natural Ways to Sleep Better
Dr. Michael Anderson, MD
Board-certified Sleep Medicine Specialist. Trained at Harvard Medical School. Focus on circadian biology, insomnia, and safe supplement use.
References
- MIT News (2001). Small doses effective for sleep aid. news.mit.edu/2001/melatonin-1017
- Sleep Foundation (2023). Melatonin dosage. sleepfoundation.org
- Zhdanova IV et al. (1996). Low-dose melatonin and sleep. Sleep 19(5):423–431. doi.org/10.1093/sleep/19.5.423
- Wade AG et al. (2011). Melatonin for sleep onset insomnia in older adults. JCEM 96(8):E1214–E1222. doi.org/10.1210/jc.2011-1106
- Andersen LP et al. (2016). Safety of melatonin in humans. Clinical Drug Investigation 36(3):169–175. doi.org/10.1007/s40261-015-0368-5
- StatPearls (2022). Melatonin. ncbi.nlm.nih.gov/books/NBK534823
- Erland LAE, Saxena PK (2017). Variability in melatonin products. J Clin Sleep Med 13(2):275–281. doi.org/10.5664/jcsm.6462
- Mayo Clinic Proceedings (2022). Melatonin safety review. mayoclinicproceedings.org
- UK NHS (2024). Side effects of melatonin. nhs.uk
