Understanding hangovers

What is a hangover?

A hangover refers to the cluster of physical, mental and emotional symptoms that occur when your blood alcohol content returns to zero, but you still feel its after-effects. Hangovers continue to puzzle and intrigue scientists because the symptoms are present after the substance has left the body, and no one is quite sure why this is.

Most people are intimately familiar with the symptoms of a hangover, but just in case you aren’t, they are:

Physical symptoms

Dry mouth, thirst, sweating, gastrointestinal problems, nausea, headaches, muscle aches, weakness, low tolerance for light and noise, disturbed sleep, shakiness, high heart rate

Mental symptoms

Difficulty thinking and concentrating, drowsiness

Emotional symptoms

Anxiety, feeling on edge and easily startled, irritability, depression.

Because many of the symptoms of a hangover overlap with the symptoms of mild withdrawal, some people claim that a hangover is a type of mini-alcohol withdrawal. However, a substance needs to be used repeatedly to induce withdrawals, while a hangover can be induced by consuming alcohol in a single session. So, what causes hangovers?

Why do we get hangovers?

The short answer is – we don’t know.

The long answer is that there are multiple competing theories about what causes individual hangover symptoms but no clear consensus on what causes them. Many overlapping processes are likely involved, which is why a hangover has so many symptoms.

Dehydration is the most common explanation put forward for hangovers, leading to the common recommendation to drink a lot of water before going to bed to prevent them. However, it has not been proven that dehydration causes hangovers. Alcohol is a diuretic and does induce dehydration, and this may explain the thirst and headaches that follow a night of drinking, but it cannot explain all of the symptoms.

Potential causes of hangovers

Dehydration

The most commonly cited source of a hangover, dehydration is implicated in causing thirst, dry mouth and headaches.

Electrolyte imbalances

Electrolytes are essential to the body and are stored in body fluids. We lose a lot of them when we drink. Electrolytes are extremely important for many vital body functions, and losing them can cause irregular heart rate, muscle aches, weakness and fatigue.

Cytokine release

Drinking causes our body to be flooded with cytokines, part of the body’s immune function. This increases inflammation and can cause headaches, fatigue and nausea.

Acetaldehyde toxicity

Alcohol is broken down into acetaldehyde in the body, which is a toxic substance. Having acetaldehyde present in the body feels unpleasant and can cause symptoms like nausea and sweating.

Congeners

Congeners are minor by-products of fermentation and distillation and are found more in certain types of alcohol. This is why people believe some drinks cause worse hangovers than others.

Lack of food

People can neglect to eat when drinking, speeding up the absorption of alcohol and leading to heavier drinking, worsening the hangover.

Other substances

Other compounds that are commonly consumed with alcohol, like nicotine, caffeine and cocaine, can worsen hangover symptoms.

Individual susceptibility

Some people are more susceptible to hangovers than others – and your susceptibility may play a role in your risk of alcohol addiction. Your susceptibility to hangovers can be dictated by your genes – and experiencing milder hangovers may not be a positive thing.

Differences in our genes can affect our tolerance to alcohol, and how severe our hangovers are. Some genes code for enzymes produced in our liver that break down alcohol. Two enzymes are important for this process – ADH1B (alcohol dehydrogenase 1B) and ALDH2 (aldehyde dehydrogenase 2). We can make different versions of these enzymes depending on our genes.

We break down alcohol in two stages. First, alcohol is converted into acetaldehyde by ADHB1 in the liver. Acetaldehyde is a ‘toxic intermediate’ – it does not feel pleasant in the body, and it’s been identified as one of the potential causes of a hangover.

In the second stage, acetaldehyde is converted into acetate by ALDH2. This clears acetaldehyde out of the body, and we feel better.

If we have a gene that codes for a variation of ADHB1 that processes alcohol into acetaldehyde quickly and effectively, we are less likely to enjoy alcohol and to become addicted to it. Unpleasant symptoms will start more quickly after drinking, meaning many people with this gene will feel that drinking alcohol isn’t worth it. Additionally, if we have a variation of ALDH2 that converts acetaldehyde to acetate quickly, we will bounce back quicker from these unpleasant symptoms, meaning the aversive effects of alcohol consumption are lessened.

Genes that cause us to experience bad hangovers from fewer drinks can protect us from the risk of alcohol addiction – while genes that cause us to experience milder hangovers can play a role in increasing our risk. The genetic component of alcohol addiction is much more complicated than these two genes, but they are part of our overall genetic risk.

Alleviating symptoms

While drinking water, resting, taking over-the-counter pain relief and eating nourishing foods can alleviate the symptoms of a hangover somewhat, there is no cure for a hangover,  and most things that people claim are cures are old wives’ tales. The only way to prevent a hangover is to drink in moderation or abstain entirely.

Hair of the dog

Hair of the dog – having another drink to stop hangover symptoms – is not a good idea. It doesn’t stop a hangover but postpones it. Your body experiences hangovers when your blood alcohol content is zero. When it’s processing alcohol, you will not feel hungover. However, when your blood alcohol reaches zero again, the hangover will resume. Frequently resorting to the hair of the dog is a warning sign that you could be experiencing alcohol addiction.

Frequent hangovers

Hangover frequency has been identified as a potential predictor of a future alcohol misuse disorder. This is not surprising – the more you drink, the more hangovers you experience, and the more likely it is that you are developing a dependence.

Some studies have looked at people who experience hangovers more frequently and found that they also get more severe hangovers. It’s unclear if this is due to them becoming sensitised to the effects of hangovers over time or if people who experience hangovers more are simply drinking more heavily due to increased alcohol tolerance, leading to worse hangovers. Either way, frequent and severe hangovers are a sign you may need to reach out for help.

Stop hangovers forever

The only surefire way to avoid a hangover is to stop drinking. If you’re worried that your hangovers are becoming too frequent and you’re finding yourself unable to stop drinking, we can help. Get in touch to find out more.