What causes a hangover? Does some alcohol cause a worse hangover?

"Why do people feel so sick the morning after drinking too much? I've heard that some alcohol can cause a far worse hangover – is that true?" 

Feeling sick after drinking too much is often referred to as a 'hangover'. A hangover can be caused by a number of factors, with one of the most important being 'toxins' contained in alcohol building up in the body. 

When you drink in moderation your body is able to protect itself from these toxins by producing enzymes that break them down and remove them from your body. Unfortunately, when the toxin level exceeds your ability to metabolise them or flush them out efficiently, you're likely to experience the unpleasant and classic symptoms of a hangover, i.e., they irritate your stomach, cause you to vomit, and generally make you feel pretty terrible.

Another factor that contributes to a hangover is dehydration (the loss of fluids from the body). It may sound strange but as you are drinking alcohol, your body is actually losing fluids. Dehydration is likely to be one of the main causes of the headaches, dizziness, and, of course, the dry mouth and thirst that many people experience. It is not known how much dehydration contributes to causing a hangover, but experts do believe that if you replace lost fluids during a night out by regularly drinking water you're likely to feel much better the next morning. 

In addition, a lack of quality sleep is likely to add to just how bad you feel the next day. When you fall asleep after a bout of heavy drinking, high levels of alcohol in your system prevent your brain from performing routine tasks, including managing your sleep pattern. This makes it difficult to reach the important REM (Rapid Eye Movement) stage of sleep. As a result, you're more likely to feel tired and grumpy when you wake up due, in part, to the lack of proper rest caused by drinking too much.

Finally, are there some alcoholic drinks that are likely to cause worse hangovers?  

Yes, there are and it's all got to do with 'congeners'. These are chemical by-products created during the alcohol fermentation process. When you drink, these toxins are released into your system as your liver breaks down the alcohol and can cause you to feel even worse. Congeners don't cause a hangover but they are believed to contribute to its impact, i.e., the fewer congeners, the 'gentler' the hangover. As a general rule of thumb, the darker the alcohol, the more congeners are present. This means that whiskey, rum and red wine which are darker in colour have more congeners than drinks with little or no colour such as vodka, gin and white wine. This explains why many wine drinkers will say that you get a far worse hangover drinking red wine than you would if you drank white.

First published: July 2021