Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Melatonin | NAC (N-Acetyl Cysteine) | |
|---|---|---|
| Category | Supplements | Supplements |
| Standard Dose | 0.3-1mg for sleep onset (physiological); 3-5mg for jet lag; 10-20mg for oncological adjunct (under supervision) | 600-1200mg daily |
| Timing | 30-60 minutes before desired sleep onset. For circadian phase advance: 4-6 hours before desired bedtime. Sublingual for faster onset. Dim lights 1-2 hours before taking. | On empty stomach for best absorption, 30 min before meals. Split doses if >600mg. |
| Cycle Duration | Short-term for jet lag (3-5 days); ongoing at low dose for circadian support if needed; extended for oncological use under supervision | Cycle 8 weeks on, 2 weeks off (to avoid potential downregulation of endogenous GSH production) |
| Evidence Level | strong_human | strong_human |
Melatonin (N-acetyl-5-methoxytryptamine) is synthesized from serotonin in the pineal gland, regulated by the suprachiasmatic nucleus (SCN) via the retinohypothalamic tract. It binds MT1 and MT2 G-protein coupled receptors: MT1 activation suppresses neuronal firing in the SCN (sleep onset), while MT2 modulates circadian phase shifting. Beyond sleep, melatonin is a potent antioxidant that scavenges hydroxyl radicals, peroxynitrite, and singlet oxygen, and upregulates antioxidant enzymes (GPx, SOD, catalase) via Nrf2. It has anti-inflammatory properties (NF-kB suppression), immunomodulatory effects, oncostatic activity (anti-proliferative in several cancer types), and mitochondrial protective functions.
0.3-1mg for sleep onset (physiological); 3-5mg for jet lag; 10-20mg for oncological adjunct (under supervision)
30-60 minutes before desired sleep onset. For circadian phase advance: 4-6 hours before desired bedtime. Sublingual for faster onset. Dim lights 1-2 hours before taking.
Short-term for jet lag (3-5 days); ongoing at low dose for circadian support if needed; extended for oncological use under supervision
NAC is a precursor to L-cysteine, the rate-limiting substrate for glutathione (GSH) synthesis via glutamate-cysteine ligase. It directly replenishes intracellular GSH, the master endogenous antioxidant. NAC also modulates glutamatergic neurotransmission by stimulating the cystine-glutamate antiporter (system Xc-), influencing extrasynaptic glutamate levels. Additionally, it acts as a mucolytic by cleaving disulfide bonds in mucus glycoproteins.
600-1200mg daily
On empty stomach for best absorption, 30 min before meals. Split doses if >600mg.
Cycle 8 weeks on, 2 weeks off (to avoid potential downregulation of endogenous GSH production)
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