My Whoop recovery is always low after drinking. What is actually happening physiologically?

Your Whoop recovery score is largely driven by RMSSD (root mean square of successive differences in RR intervals), which measures parasympathetic nervous system activity. Low RMSSD the morning after drinking reflects acetaldehyde toxicity-driven sympathetic activation and suppressed vagal tone. The parasympathetic nervous system, the "rest and recover" system, is directly inhibited by acetaldehyde, the primary toxic metabolite of alcohol metabolism.

While you are drinking, the sedative effect of alcohol suppresses cortisol and slows the heart, producing the subjective feeling of relaxation. But alcohol is metabolized to acetaldehyde within hours, and acetaldehyde is cardiotoxic. It directly activates the sympathetic nervous system, increases atrial ectopy, suppresses deep sleep, and produces the disrupted cardiovascular state that your Whoop registers as poor recovery by morning. The watch is not being oversensitive. It is accurately measuring a physiological disruption you cannot feel consciously because it happens during sleep. (Altini and Kinnunen, JMIR Mhealth Uhealth, 2021)

Cardiologist's calibrated position, Solid (1). The RMSSD suppression from alcohol is directly measurable and mechanistically explained. The Whoop data is reliable on this specific question.

What to do: Check your resting heart rate on drinking mornings versus non-drinking mornings alongside your RMSSD. If your resting heart rate is 6–10 bpm higher on drinking mornings, that elevation represents a direct cardiovascular tax on your sleep period.

For the full picture, read The Bourbon Collector's Honest Reckoning.