What factors can contribute to hangover?

There are several factors that are known to contribute to alcohol hangover, though they’re probably not a direct cause.

Excessive alcohol consumption leads to dehydration, fluctuations in electrolyte levels, and alterations in blood glucose which in turn can lead to thirst, dizziness, headaches, and problems with memory and concentration – all of which are symptoms that have been reported during hangover.

Alcohol also reduces sleep quantity and quality, which may explain the symptom of next-day drowsiness in people experiencing hangovers.^[1]

Genetic factors may also influence a person’s propensity to be “hangover-resistant” or “hangover-prone”; anywhere from 5–23% of the population are reported to be “hangover-resistant”.^[2] One study found that genetic factors accounted for 40–45% of the variation in hangover frequency and 16–24% of the variation in hangover susceptibility among individuals.^[3]

Congeners are naturally occurring compounds in most alcoholic beverages produced during the distilling and fermenting process; examples include methanol, esters, tannins, histamines, and aldehydes.^[4] Some theories posit that congeners may compete with alcohol metabolism and/or cause inflammation. Some studies suggest that alcohols with more congeners (i.e., brandy, red wine, rum, bourbon) may lead to worse hangovers than those with the least congener content (i.e., vodka, beer, gin, white wine), but not all evidence suggests that this is true.^[5]