Alcohol hangover is such a common issue there is a movie trilogy named after it. Very few people, however, will see or experience the full extent of withdrawal. Characterized by fatigue, headaches, light sensitivity, nausea and bad sleep, hangovers are felt by 25.5% of college students each week (Swift and Davidson, 1998; Meilman, et al., 1990). It is important to make the distinction between hangover and alcohol withdrawal: hangovers are experienced after one instance of alcohol consumption, whereas alcohol withdrawal is only felt after a long period (multiple days) of heavy alcohol consumption. In nature, hangover is almost always part of withdrawal but hangover is not itself withdrawal (Swift and Davidson, 1998). Alcohol withdrawal has much worse symptoms, including seizures and delirium (Myrick and Anton, 1998). Alcohol withdrawal can also be life-threatening without medical treatment, while hangovers are not life-threatening.

The mechanisms of both hangover and larger withdrawal stem from Himmelsbach’s concept that drugs create a shift in the homeostatic equilibrium of the body that the body adjusts to (Himmelsbach, 1941).  When the alcohol is then removed, it exposes these mechanisms and creates another imbalance in homeostatic equilibrium. In the case of alcohol, the ‘acute alcohol effect’ or desired intoxication is the first unbalancing of the brain. If allowed to return to normal without much or any more consumption, it will produce at most a hangover. On the contrary, if exposure continues significantly longer, then the brain will make considerable neurochemical adaptations as seen in Figure 1. When the consumption stops after a long time, it will create a neurochemical unbalance in the other direction which is withdrawal.  In alcohol consumption, one of the neurotransmitters affected is called gamma-aminobutyric acid (GABA) and it is an inhibitory neurotransmitter. When alcohol is introduced, GABA’s effect is exacerbated and the neurons that it impacts will be even more inhibited. This will impede brain activity in many parts of the brain which is most likely responsible for some of the symptoms of the acute alcohol effect (Littleton, 1998).

It must be noted that it will take a somewhat significant quantity of alcohol to achieve a hangover and even more to achieve withdrawal. The individual amount required for each threshold can also vary between individuals and between instances for the same individual. It is not very well understood what exactly is responsible for the differing hangover severity that many individuals experience but it has been shown that at least zinc and niacin reduce hangover severity the next day (Verster, et al., 2019). There are also other factors such as sleep disturbance as a result of the drinking environment and family history that have been shown to influence hangover severity or lack thereof (Swift and Davidson, 1998). Alcohol withdrawal, or at least its treatment, is somewhat better understood for multiple reasons. Withdrawal can be observed for many drugs so its characteristics can be compared and inferred between cases, whereas hangover is exclusively a symptom of alcohol consumption. This in combination with its lack of mortality make it a perplexing but benign issue.

Alcohol hangover and withdrawal are two different but overlapping conditions that occur after alcohol consumption stops. They both implicate the GABA neurotransmitter but alcohol withdrawal is much more severe. Hangover is much more common, especially among university students; however, it does not require treatment, despite its impacts on productivity.

References :

Himmelsbach, C.K., 1941. The morphine abstinence syndrome, its nature and treatment. Annals of Internal Medicine, 15(5), pp.829–839. https://doi.org/10.7326/0003-4819-15-5-829.

Littleton, J., 1998. Neurochemical mechanisms underlying alcohol withdrawal. Alcohol Health and Research World, 22(1), pp.13–24.

Meilman, P.W., Stone, J.E., Gaylor, M.S. and Turco, J.H., 1990. Alcohol consumption by college undergraduates: Current use and 10-year trends. Journal of Studies on Alcohol, 51(5), pp.389–395. https://doi.org/10.15288/jsa.1990.51.389.

Myrick, H. and Anton, R.F., 1998. Treatment of alcohol withdrawal. Alcohol Health and Research World, 22(1), pp.38–43.

Swift, R. and Davidson, D., 1998. Alcohol hangover. Alcohol Health and Research World, 22(1), pp.54–60.

Verster, J.C., Vermeulen, S.A., van de Loo, A.J.A.E., Balikji, S., Kraneveld, A.D., Garssen, J. and Scholey, A., 2019. Dietary nutrient intake, alcohol metabolism, and hangover severity. Journal of Clinical Medicine, 8(9), p.1316. https://doi.org/10.3390/jcm8091316.