What Exactly Happens During a Hangover?

We’ve all had those mornings: opening our eyes to a world that’s spinning a bit too much, a headache that’s pounding like a drum, and a distinct feeling of regret. Yes, welcome to your hangover.

But have you ever wondered, what exactly is a hangover? And why do hangovers happen in the first place? In this post, we’ll explore what happens during a hangover, how severe hangover symptoms develop, and what we can do about it. Let’s dive in!

Why Do Hangovers Happen?

To understand what happens during a hangover, we first need to understand how our body processes alcohol. Why? Because even though it’s easy to forget, alcohol is actually a toxin. Every time we drink, we’re essentially poisoning ourselves. It’s no wonder we don’t feel well the next day!

Here’s how it works: when we drink, our bodies break down alcohol into several compounds, the first of which is acetaldehyde, a potent toxic chemical. While alcohol is a toxin in its own right, acetaldehyde takes it up a notch — we're talking 30 times more toxic.

The acetaldehyde is further broken down into acetate, a relatively non-toxic substance, which is eventually converted into carbon dioxide and water. But here's the catch: our body can only process alcohol so quickly. In fact, our liver can only efficiently process one standard-sized alcoholic drink per hour. If we’re downing shots like there's no tomorrow, acetaldehyde accumulates faster than our body can eliminate it. The result? A hangover!

How Alcohol Causes Hangover Symptoms

Now that we have a general understanding of how our body processes alcohol, let’s take a closer look at how alcohol causes some of the more specific symptoms when you are nursing a hangover. So, how does it feel to be hungover?

• Dilates blood vessels: The drumming inside our skull is probably one of the most common hangover symptoms. This is because alcohol expands our blood vessels, a process known as vasodilation. This leads to increased blood flow in the brain, resulting in a pounding headache. It's as if your brain is throwing its own little protest march — complete with drums and trumpets! — against your overindulgence.
• Dehydrates us: Ever woken up after a night of drinking feeling like you have a mouthful of dust? We can thank alcohol’s dehydrating effects. This is because alcohol is a diuretic: it promotes water loss through urination (hence all those trips to the bathroom!). But peeing out our fluids makes us dehydrated, leaving our mouth as dry as a desert and intensifying that spinning-room sensation the next day.
• Leads to inflammation: Remember that toxic chemical called acetaldehyde? As it accumulates in our liver, it can cause inflammation in our liver, pancreas, brain, GI tract, and other organs. Alcohol also increases the production of endotoxins, inflammatory chemicals in the body. Inflammation is why we might feel particularly groggy and lethargic the morning after drinking.
• Impairs immune system: Alcohol can also impair our immune system, which contributes to symptoms of a headache, nausea, and fatigue. In fact, research has found that drinking too much can trigger our immune system to release chemicals called cytokines. Increased levels of cytokines have been found to affect memory and concentration, as well as causing symptoms of nausea, headache, chills and tiredness.
• Disrupts sleep: Alcohol might help us fall asleep faster, but it actually interferes with our sleep cycle by disrupting the rapid eye movement (REM) stage of sleep, which is crucial for getting a good night’s rest. Even if we’ve technically had a full night's sleep, it can feel like we’ve pulled an all-nighter.
• Irritates our stomach: That unsettled stomach after a night of drinking? That's the booze wreaking havoc again. Alcohol increases gastric acid in our stomach, slowing the rate at which our stomach empties itself and inflaming the stomach lining. This can lead to nausea, vomiting, or even diarrhea.
• Lowers blood sugar: Alcohol causes our blood sugar to drop, leading to mood swings, irritation, and general crankiness. Low blood sugar is also associated with fatigue and dizziness. And that's not to mention the anxiety and regret that can accompany trying to piece together the events of last night (hangxiety, anyone?).
• Worsens mood: Alcohol is a depressant, and it works by slowing the brain's functions. While we might initially feel relaxed and cheerful, as the alcohol levels drop in our body, the reverse happens. And by the time we wake up, we might feel restless, anxious, or even depressed. It's like a roller-coaster: the high might be exhilarating, but the drop can leave us feeling low.

Overall, alcohol creates a cascade of effects that throws both our body and mind off balance, making it all the more crucial to consider if the momentary high of drinking is worth the physical discomfort and emotional toll the next day.

Factors That May Increase Our Risk of Hangovers

Are some people more likely to develop a hangover than others? Perhaps you’ve noticed that your friend seems to get away with several drinks without experiencing much of a hangover the next day. But maybe for you, as little as one drink can trigger a hangover. Why is this?

A variety of factors influence both the likelihood and severity of experiencing a hangover. Let’s take a closer look at 8 of them:

1. Level of consumption: While alcohol can affect people differently, as a general principle, the more alcohol we consume, the higher our chances of having a hangover and the more severe it’s likely to be. Three glasses of wine are more likely to cause a pounding headache than just one. 
2. Genetics: Our genetics play a big role in alcohol’s effects on our body. For instance, people of Asian descent have a genetic variation that makes it more difficult to break down acetaldehyde — that toxic chemical. As little as one drink can cause flushing, sweating, and even vomiting. 
3. Gender: Some research suggests that women are more likely to experience hangovers than men. This could be because women process alcohol differently than men and are more sensitive to its effects: they tend to have less acetaldehyde dehydrogenase (ALDH), an important enzyme for metabolizing alcohol in the stomach.
4. Age: Our age can make a difference. The older we are, the longer alcohol stays in our liver before it is metabolized or moves into our general bloodstream. Typically, older people have lower percentages of body water compared to those who are younger, which can also contribute to a higher blood alcohol content (BAC) and a slower processing time.
5. Health status: Some research suggests that hangovers correlate with poorer self-reported health status. In other words, our overall level of health can play a role in how alcohol affects us the next day.
6. Use of other drugs: Smoking cigarettes or using drugs may exacerbate a hangover. In fact, these substances can cause their own set of hangover-like symptoms, so combining them with alcohol is like a double whammy. 
7. Personality traits: Interestingly, research shows that certain personality traits, such as shyness, seem to intensify hangover feelings — particularly that sense of “hangxiety.” Negative life events, feelings of guilt, and the risk of alcoholism also tend to produce acute hangover symptoms. 
8. Time of day: Our circadian rhythm plays a role in how our body processes alcohol. Research has shown that the most effective time of day for our body to metabolize alcohol is the early to middle evening hours (i.e. happy hour!). If we consume alcohol late into the night or in the morning, our body has a harder time processing it. As a result, we might experience more intense hangover symptoms. 

Do Some Types of Alcohol Cause Worse Hangovers Than Others?

While any type of alcohol can cause a hangover, certain types may be more likely to lead to severe hangover symptoms. This is because different types of alcohol have different congeners — toxins that result from the fermentation process. When we consume congeners, extra stress is put on our liver to break down these substances and restore normal body function, which becomes the reason for the hangover.

Research shows that congeners are associated with more severe hangover symptoms, such as nausea and dizziness. For instance, one study compared participants’ self-reported hangover severity after drinking bourbon or vodka. Researchers found that participants who drank bourbon — which is high in congeners — reported feeling worse than those who drank vodka, which has almost no congeners at all.

In general, congeners are found in higher concentrations in darker alcoholic drinks. Beware of these darker drinks, which can cause the worst hangovers:

• Bourbon
• Brandy
• Whiskey
• Tequila 
• Red wine
• Dark beer

Clear liquors, such as vodka and gin, have comparatively lower concentrations of congeners. Bourbon whisky, for example, contains 37 times the quantity of congeners as vodka.

Tips for Preventing Hangovers

While the best way to avoid a hangover is to limit our consumption of alcohol (or not drink!), we can take action to lessen their intensity. Here are 5 tips:

1. Stay hydrated. Make sure you’re drinking water before, during, and after your alcoholic escapades. This can help stave off the worst of the dehydration.
2. Don’t drink on an empty stomach. Eating before or while drinking slows alcohol absorption, giving your body more time to handle it.
3. Choose wisely. Stick to lighter-colored drinks. Darker ones contain more congeners — those compounds that can intensify a hangover.
4. Pace yourself. Try limiting your alcohol intake to one drink per hour. It can prevent acetaldehyde from building up in your body too quickly.
5. Set drinking limits. Decide in advance how many days a week and how many drinks per occasion you'll have. Stick to these limits!

Smart drinking practices can both help prevent a hangover and keep us safe. But we also might consider investigating the “sober curious” movement that has been gaining traction in recent years, particularly among the younger generation. Being “sober curious” isn’t necessarily about saying goodbye to drinking for good, but about re-evaluating our relationship with alcohol and being more intentional about why and how often we choose to drink.

What’s the Best Hangover Remedy?

What if the night got out of hand and you ended up drinking more than you anticipated? It’s now the next day and you feel like you’re going to vomit. Is there a hangover remedy?

Let’s look at 5 things we can do to cope with a hangover when we’re in the middle of one:

1. Hydrate, hydrate, hydrate: Water might not sound particularly appealing, but it’s vital to rehydrate after a night of drinking. Consider adding electrolytes to your water to replenish lost fluids and minerals. Electrolyte-rich sports drinks such as Gatorade, Pedialyte, or Powerade are also good options.
2. Eat breakfast: Food might be the last thing on our minds when we’re nursing a hangover, but a balanced breakfast can be a game-changer. Choose foods rich in vitamins, minerals, and protein, which can help restore depleted nutrients and stabilize blood sugar levels. Think eggs, smoothies, or bananas. 
3. Recharge with sleep: Even if we feel like we slept, chances are we didn’t get quality sleep, since alcohol suppresses REM sleep. When we’re hungover, catching up on sleep can be one of the best remedies. Sleep allows our body to heal, and a hangover is no exception. 
4. Get moving (slowly!): While the thought of any physical activity during a hangover might seem daunting, a gentle walk or a slow-paced yoga session can do wonders. Movement helps boost circulation, improves our mood, and speeds along the hangover recovery process. 


Avoid the “hair of the dog”: It might be tempting to have another drink to ease hangover symptoms, but this only prolongs our recovery. Resist this temptation and allow your body time to heal by steering clear of alcohol for at least the next few days.

The Bottom Line

Hangovers aren’t just a nuisance: they’re a stark reminder that your body doesn’t appreciate being flooded with toxins. But don’t worry — it’s not about never enjoying a night out again. It's about making better choices when you do. Understanding the science behind hangovers can provide a valuable tool in our quest to cut back or quit drinking altogether. So, the next time you consider that extra round, remember what awaits you the morning after.

If you’re struggling to manage your alcohol consumption, consider trying Reframe. We’re a science-backed app that has helped millions of people cut back on their alcohol consumption and enhance their physical, mental, and emotional well-being.