What causes a hangover
A hangover is not one mechanism. It's the metabolic and sleep-architecture aftermath of an evening's drinking — four distinct biological insults that overlap on the same morning, plus a fifth (acetaldehyde) that runs only during the active clearance window.
What is happening
The folk model — "a hangover is leftover acetaldehyde" — is wrong for most people. ALDH2 finishes the job before you wake up. What you feel in the morning is the metabolic and sleep-architecture aftermath of that clearance.
The four drivers of next-morning misery
- Sleep architecture damage. Alcohol metabolism elevates body temperature, suppresses REM, and fragments deep sleep — primarily during the clearance phase. If clearance happens during sleep, sleep is destroyed. This is the largest felt-difference lever.
- Hydration and electrolyte loss. Ethanol suppresses ADH/vasopressin → free-water clearance up → hyponatremia and hypokalemia. Pre-bed electrolyte load preempts the morning deficit.
- NAD⁺ depletion. Ethanol metabolism consumes NAD⁺ at both ADH and ALDH2 steps, crashing the NAD⁺/NADH ratio. Gluconeogenesis stalls; SIRT3 activity drops; ALDH2 throttles even when enzyme is abundant.
- Gut-derived inflammation. Alcohol opens gut tight junctions, allowing bacterial LPS into portal circulation. Systemic cytokine response feels like flu — it's the "I've been hit by a bus" component.
The fifth driver: acetaldehyde (active clearance window only)
Your liver metabolizes ethanol in two stages. ADH converts ethanol → acetaldehyde; ALDH2 converts acetaldehyde → acetate. ADH is fast; ALDH2 is the bottleneck. While clearance is in progress, acetaldehyde — a Group-1 carcinogen — accumulates and contributes to the flush, fast heartbeat, and nausea most people feel during drinking and the hours immediately after. In non-ALDH2*2 livers, ALDH2 finishes the job within hours; the "hangover" you wake up with is the four drivers above, not unfinished acetaldehyde clearance.
Ingredients that address this, ranked
- Electrolytes Tier 1 · Core Impact: high — Hydration driver. Counters vasopressin suppression; replaces sodium and potassium lost to alcohol diuresis.
- Nicotinamide Riboside (NR) Tier 1 · Core Impact: high — NAD⁺ driver. Restores the cofactor pool ALDH2 and the TCA cycle need.
- NAC (N-Acetyl Cysteine) Tier 1 · Core Impact: high — Glutathione precursor protecting ALDH2's catalytic Cys302; acetaminophen safety net.
- Drink timing Tier 0 · Prerequisite Impact: highest — Sleep-architecture driver. Last drink ≥3 hours before bed. No supplement substitutes for this.
How tiers compare for this mechanism
| Goal | Best (Tier 1) | Strong support (Tier 2) | Situational (Tier 3+) |
|---|---|---|---|
| Sleep architecture | Drink timing (prerequisite) | Magnesium glycinate, Glycine | |
| Hydration & electrolytes | Electrolytes | Magnesium glycinate | |
| NAD⁺ restoration | Nicotinamide Riboside (NR) | ||
| Inflammation control | NAC (N-Acetyl Cysteine), Sulforaphane | Zinc carnosine | |
| Acetaldehyde clearance | NAC, Sulforaphane (preflight only), NR | L-Cysteine, DHM, Glycine | |
| Neurotransmitter modulation | DHM, Magnesium glycinate, Glycine |
Deeper science · In more detail
Which driver explains which symptom
- "I slept eight hours and feel destroyed" — sleep architecture damage. REM was suppressed and deep sleep was fragmented; the duration was nominal but the recovery work didn't happen.
- Headache, dry mouth, dizziness on standing — dehydration and electrolyte loss. Free-water clearance ran high overnight; sodium and potassium are below baseline.
- Fatigue, exercise intolerance, "the carbs didn't help" — NAD⁺ depletion. Gluconeogenesis is stalled and the TCA cycle is bottlenecked at the cofactor level.
- Body aches, low-grade nausea, "flu feeling" — LPS-driven inflammation. Gut barrier disruption let bacterial endotoxin into portal circulation.
- Flush, fast heartbeat, sweats during drinking and the first few hours after — acetaldehyde, while ALDH2 is still working through the load. This component is largely gone by morning.
- 3am wakeups, next-day anxiety — GABA-A rebound and glutamate surge after ethanol leaves the system; a separate mechanism stacked on top of the four drivers.
What to do about it
The protocol routes against every driver, weighted by felt impact per unit effort:
- Sleep architecture — the lever is behavioral. Stop drinking ≥3 hours before bed; drink timing dominates supplement choice. Magnesium glycinate is the supplement-side adjunct.
- Hydration — pre-bed electrolyte load; sodium and potassium with water. Single highest-leverage non-prescription intervention.
- NAD⁺ — NR (or NMN) restores the cofactor pool ALDH2 and the TCA cycle need.
- Inflammation — zinc carnosine tightens the gut barrier; NAC and sulforaphane dampen the downstream cytokine response.
- Acetaldehyde (active window only) — ALDH2 cofactor support via NR; protection via NAC; pre-induction via sulforaphane. Local trapping (L-cysteine, glycine) is a Tier 2 adjunct, not the primary clearance pathway.