Comparison
Melatonin vs N-Acetyl Cysteine
Side-by-side of Melatonin and N-Acetyl Cysteine. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Melatonin
Melatonin as a sleep supplement: 0.3-1 mg matches physiological output, 3-10 mg is pharmacological. Shifts circadian phase, shortens sleep latency.
N-Acetyl Cysteine
NAC supplement benefits cover glutathione synthesis, liver and antioxidant support, and hangover recovery. Evidence strongest at 1200-2400 mg/day.
Effects at a glance
Melatonin
- •Shortens sleep onset latency by ~7 to 12 minutes at physiological 0.3 to 1 mg doses
- •Advances circadian phase when taken 30 to 60 minutes before target bedtime, useful for jet lag and shift work
- •Does not meaningfully increase total sleep time in healthy adults without circadian misalignment
- •Endogenous nighttime production is not suppressed by short-term exogenous supplementation
- •Higher doses (3 to 10 mg) raise plasma levels above physiological range and often increase morning grogginess
- •Effective for delayed sleep-wake phase disorder and reducing jet-lag severity in eastward travel
N-Acetyl Cysteine
- •Replenishes intracellular glutathione by supplying cysteine, the rate-limiting amino acid for synthesis
- •First-line antidote for acetaminophen toxicity, restoring hepatic glutathione before fulminant injury occurs
- •Reduces sputum viscosity in chronic bronchitis and COPD at 600 to 1200 mg/day over months
- •Modest symptom reductions in OCD and trichotillomania at 1200 to 2400 mg/day across small RCTs
- •Mixed evidence for psychiatric adjunct use in bipolar depression and schizophrenia negative symptoms
- •Inhaled forms can trigger bronchospasm in active asthma; oral use is the standard biohacker route
Side-by-side
| Attribute | Melatonin | N-Acetyl Cysteine |
|---|---|---|
| Category | supplement | supplement |
| Also known as | N-acetyl-5-methoxytryptamine | NAC |
| Half-life (hr) ↗ | 0.75 | 5.6 |
| Typical dose (mg) ↗ | 0.5 | 1200 |
| Dosing frequency | daily, 30 to 60 minutes before target sleep time | 1 to 3 times daily, split dosing preferred |
| Routes | oral, sublingual | oral, iv |
| Onset (hr) | 0.5 | 1 |
| Peak (hr) | 1 | 2 |
| Molecular weight | 232.28 | 163.19 |
| Molecular formula | C13H16N2O2 | C5H9NO3S |
| Mechanism | Agonist at MT1 and MT2 receptors in the suprachiasmatic nucleus, signaling biological night and promoting sleep-onset gating plus circadian phase shifts. | Deacetylated to cysteine, the rate-limiting precursor for glutathione synthesis; also directly scavenges reactive oxygen species and modulates glutamate signaling. |
| Legal status | OTC in US; prescription in UK, EU, Japan | OTC in most jurisdictions; restricted periods in US history (FDA reclassified 2022) |
| WADA status | allowed | allowed |
| DEA / Rx | OTC supplement in US; Rx in UK, EU, Japan, Australia | OTC supplement (US, post-2022); Rx indications also exist (acetaminophen overdose, mucolytic) |
| Pregnancy | Insufficient data; not routinely recommended | Used clinically in pregnancy for specific indications; consult clinician |
| CAS | 73-31-4 | 616-91-1 |
| PubChem CID | 896 | 12035 |
| Wikidata | Q179243 | Q413299 |
Safety profile
Melatonin
Common side effects
- vivid dreams
- morning grogginess (higher doses)
- headache
- dizziness
Contraindications
- autoimmune disease (theoretical)
- concurrent anticoagulant therapy without monitoring
Interactions
- fluvoxamine: CYP1A2 inhibition raises melatonin levels substantially(major)
- warfarin: possible increased bleeding risk(moderate)
- benzodiazepines and alcohol: additive sedation(moderate)
- antihypertensives: may alter blood pressure response(minor)
N-Acetyl Cysteine
Common side effects
- sulfur-like taste or odor
- nausea
- flatulence
- diarrhea
Contraindications
- active asthma attack (inhaled form can trigger bronchospasm)
- known NAC hypersensitivity
Interactions
- nitroglycerin: potentiates vasodilation, risk of hypotension and headache(moderate)
- activated charcoal: reduces NAC absorption when used for acetaminophen overdose(moderate)
- anticoagulants: theoretical additive antiplatelet effect at high doses(minor)
Which Should You Take?
N-Acetyl Cysteine comes out ahead for most readers on the criteria we weight: 3 catalogued goals, OTC, oral dosing, with a Tier-A outcome catalogued. Melatonin is the right call when one of the conditionals below applies.
- → If your priority is sleep onset or sleep quality, pick Melatonin.
- → If your priority is circadian regulation, pick Melatonin.
- → If your priority is healthspan extension, pick N-Acetyl Cysteine.
- → If your priority is post-training recovery, pick N-Acetyl Cysteine.
Edge case: Half-lives differ materially (Melatonin ~0.75 hr vs N-Acetyl Cysteine ~5.6 hr). N-Acetyl Cysteine reaches steady state faster; Melatonin is easier to dial in if tolerability is uncertain.
Default choice: N-Acetyl Cysteine. Wider use case, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for Melatonin only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Melatonin and N-Acetyl Cysteine?
Melatonin and N-Acetyl Cysteine differ in category (supplement vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Melatonin or N-Acetyl Cysteine?
Melatonin half-life is 0.75 hours; N-Acetyl Cysteine half-life is 5.6 hours.
Can you stack Melatonin with N-Acetyl Cysteine?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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