The Science Behind Hangovers: Why They Last as Long as They Do

From the slapstick scenes in comedies to dramatic morning-after moments in romance films, Hollywood has a knack for portraying hangovers in ways that range from the hilariously exaggerated to the eerily accurate. Who can forget the disheveled crew in The Hangover, waking up in a trashed Las Vegas suite with absolutely no memory of the night before? Or Bridget Jones in Bridget Jones's Diary lamenting her choices from the previous night, nursing a headache with a glass of water and an aspirin? 

While these films offer entertaining portrayals of the payback that comes after a night of heavy drinking, they only scratch the surface of what's actually happening in our bodies. Let's pull back the curtain on the silver screen and shine a spotlight on the science behind those groggy, head-pounding mornings. We’ve got the 6 scientific reasons why hangovers last as long as they do.

Part 1: Hangovers: The Post-Drink Timeline

While hangover symptoms can vary, they follow a general timeline, often unfolding in a predictable sequence. 

6-8 hours post-drinking:

• Thirst and dry mouth. As alcohol's diuretic effects kick in, dehydration appears.
• Fatigue. The disruptive effect of alcohol on sleep starts to show.

8-10 hours post-drinking:

• Headache and dizziness. These symptoms result from dehydration and the dilation of blood vessels.
• Nausea and stomach pain. The effect of alcohol irritating the stomach lining begins to peak.

10-12 hours post-drinking:

• Sensitivity to light and sound. The nervous system reacts to the booze with heightened sensory perceptions.
• Mood disturbances. Depression, anxiety, and irritability might arise as alcohol levels drop.

12-24 hours post-drinking:

• Increased thirst. The body’s attempt to counteract dehydration continues.
• Muscle aches. Reduced glucose levels might lead to weakness or muscle cramps.

24-48 hours post-drinking (if we really overdid it):

• Severe fatigue. Tiredness continues due to the interrupted sleep cycle and the body's effort to rid itself of toxins.
• Stomach issues. Continued nausea or vomiting might persist.

Part 2: The Science Behind Hangovers

Now that we have a general idea of what hangovers are like, let’s explore the science behind them and learn more about the lasting effects of alcohol on our body chemistry.      

1. Alcohol Causes Dehydration

It might seem counterintuitive at first — we drink liquid, but end up feeling parched the next day. In the case of alcohol, though, this paradoxical effect is very real, and it comes down to how booze interacts with our bodies.  

• The ADH story. Alcohol inhibits the secretion of the antidiuretic hormone, ADH, which helps our kidneys reabsorb water to keep us hydrated. By suppressing ADH production, alcohol decreases the kidneys’ ability to reabsorb water, leading to excessive urine production. This increase in urine output results in more frequent trips to the restroom and a net loss of body fluids.  
• Electrolyte imbalance. The repercussions of increased urination go beyond fluid loss. We also lose essential salts and minerals — particularly sodium, potassium, and magnesium. These electrolytes are vital for physiological functions such as muscle contraction, neural transmission, and fluid balance. When their levels are depleted, we end up with symptoms such as muscle cramps, dizziness, and nausea.
• Toxins. Dehydration can exacerbate the irritating effects of alcohol by-products. Our body uses water to process and eliminate toxins. With dehydration caused by alcohol, our system might not effectively get rid of these harmful substances, prolonging the hangover effects.

2. Acetaldehyde Buildup

When we drink, the liver immediately starts using enzymes to break it down in a two-step process. More toxic than alcohol itself, acetaldehyde — the intermediary metabolic by-product — is one of the primary culprits behind unpleasant hangover symptoms. The more we drink, the harder it is for the liver to keep up. As a result, acetaldehyde accumulates in the bloodstream, leading to nausea, sweating, and skin flushing.

Some people are also genetically more susceptible to acetaldehyde buildup, especially if they have a less-active variant of the liver enzymes. This genetic variation is responsible for the facial flushing, dizziness, and nausea that comes with consuming even small amounts of alcohol.

Apart from its direct toxic effects, acetaldehyde also promotes inflammation, which can exacerbate hangover symptoms, contributing to fatigue, memory issues, and decreased attention span.

3. Sleep Disruption

Alcohol may seem like an ideal sleep aid, helping us doze off quickly. But while it might make us crash, the quality and structure of the sleep we get isn’t the best — we wake up feeling groggy, even if we slept longer than usual. Let’s explore how alcohol contributes to hangover-related fatigue in more detail.

• Alcohol and REM sleep. Alcohol interferes with the REM (rapid eye movement) phase of sleep — a vital stage of the sleep cycle associated with dreaming, memory consolidation, and emotional processing — by sending us into deep sleep almost immediately. However, as the alcohol wears off, we experience "REM rebound": the brain increases the duration and frequency of REM stages in the latter half of the night, resulting in a choppy, disrupted sleep pattern. This REM rebound can lead to more vivid dreams (or nightmares!) and a higher likelihood of waking up throughout the later part of the night.
• Frequent bathroom trips. The diuretic effect of alcohol we talked about earlier can also interrupt sleep, as trips to the bathroom become more frequent.
• Sleep apnea and breathing issues. Alcohol relaxes the muscles in the throat, causing snoring and exacerbating conditions like sleep apnea. Those with undiagnosed or diagnosed sleep apnea may experience more frequent or severe interruptions in breathing when drinking before sleep and find themselves waking up multiple times throughout the night.
• The morning after. A night of fragmented sleep often results in fatigue the next day, leading to irritability, poor concentration, and mood disturbances.

4. Immune System Response

Drinking can activate the immune system, causing it to respond as if there's a threat. This activation triggers a cascade of effects that make us feel lousy, contributing to hangover symptoms such as malaise, fatigue, and cognitive disruptions. The immune response is part of the reason why, after a night of drinking, we might feel like we’re coming down with something, even if we aren’t.

• Inflammation. Alcohol can trigger the release of pro-inflammatory cytokines — proteins that play a crucial role in cellular communication during immune responses. Specifically, alcohol increases the secretion of tumor necrosis factor (TNF), interleukin-1 (IL-1), and interleukin-6 (IL-6), elevated levels of which result in fatigue, headache, and loss of appetite.
• Gut barrier disruption. The gut houses a significant portion of our body’s immune cells. Alcohol can disrupt the gut barrier, allowing endotoxins to enter the bloodstream. Once in the bloodstream, these endotoxins can elicit a strong immune response, contributing further to the production of pro-inflammatory cytokines.
• Impact on white blood cells. Alcohol can impact the quantity and function of white blood cells — particularly macrophages and neutrophils, the frontline defenders against infections. With their function hampered, infections take hold more easily and recovery times from illnesses get longer.

5. Stomach Troubles

For many, a night of drinking is often followed by the all-too-familiar unpleasantness of an upset stomach the next day. But what exactly does alcohol do to our stomach to cause this discomfort?

• Stomach acid production. One immediate effect of drinking is an increase in the production of stomach acid. While stomach acid is essential for digesting food, an excess can lead to gastritis (inflammation of the stomach lining). The symptoms of gastritis include pain, bloating, and nausea.
• Stomach motility. Alcohol affects stomach motility by making it less efficient at moving food and drink through the digestive tract. This delay can result in bloating and fullness, adding to withdrawal-related stomach discomfort.
• Impact on the gut lining. Alcohol can thin the protective mucus layer of the stomach, making it more susceptible to the corrosive effects of acid. Over time and with chronic consumption, this can lead to ulcers.
• Interaction with digestive enzymes. Alcohol can interfere with the secretion of digestive enzymes that are vital for the breakdown of food in the small intestine. Reduced enzyme activity can lead to digestive disturbances.
• Alcohol and the gut microbiome. Recent research has highlighted the profound impact of alcohol on our gut microbiota — the community of beneficial microbes that reside in our digestive tract. It can disrupt the balance between beneficial and harmful bacteria, which can lead to gut-related issues.

6. Drops in Blood Sugar

A night of drinking can leave us feeling unusually fatigued, dizzy, or shaky. One often overlooked culprit for these sensations? A drop in blood sugar levels. 

The liver plays a crucial role in regulating blood sugar. One of its primary responsibilities is to release stored glucose into the bloodstream when blood sugar levels drop, ensuring a steady energy supply for the body’s functions. However, when alcohol is introduced, the liver prioritizes metabolizing it over other tasks, including gluconeogenesis — the process by which the liver produces glucose from non-carbohydrate sources. Alcohol consumption can inhibit gluconeogenesis, reducing the liver's ability to produce and release new glucose into the bloodstream.

As a result of these factors, alcohol can lead to hypoglycemia, a condition characterized by abnormally low blood sugar levels. Symptoms of hypoglycemia include weakness, dizziness, sweating, rapid heartbeat, and confusion. If left untreated, severe cases can lead to fainting or seizures.

The type of alcoholic beverage consumed, and what it's consumed with, can also impact blood sugar levels. Drinks with high sugar content can initially spike blood sugar, followed by a sharp drop. Moreover, if alcohol is consumed on an empty stomach, the risk of hypoglycemia increases as there's no accompanying food to stabilize glucose levels.

Chronic alcohol consumption can also change how the body responds to insulin, the hormone that allows cells to take in glucose from the bloodstream. Alcohol can increase insulin secretion, leading to a more rapid decrease in blood sugar levels, impairing the insulin signaling pathway, and possibly even leading to insulin resistance.

An Ounce of Prevention Is Worth a Pound of Cure

While understanding the science behind hangovers is important, wouldn’t it be even better if we could sidestep them altogether? Let’s explore some science-backed strategies that can help.

• Stay hydrated. Stay on top of your hydration game! Drinking water before, during, and after your alcoholic beverages can counteract the diuretic effect of alcohol and reduce dehydration.
• Eat before you drink and replenish with nutrients. Having a meal before drinking can slow the absorption of alcohol, reducing peak blood alcohol concentration. Opt for a balanced meal with proteins, fats, and complex carbs. Also, consider having a balanced breakfast the next morning. Foods like bananas, avocados, and eggs can help replenish essential nutrients.
• Supplement smartly. While they’re no magic pill, some supplements can help your body better process alcohol. B-vitamins, vitamin C, and magnesium can replenish what alcohol depletes.
• Choose light over dark and skip the bubbles. Congeners, by-products of alcohol fermentation, are believed to exacerbate hangovers. They're found in higher amounts in dark spirits than clear ones. Also, fizzy alcoholic drinks can speed the absorption of alcohol. Maybe that champagne isn’t such a great idea after all!
• Set a limit and stick to it. Knowing your limits is a way to ensure you have fun without regret.
• Alternate with non-alcoholic beverages. For every alcoholic drink, have a non-alcoholic one. This helps you pace yourself and stay hydrated.  

At-Home Hangover Remedies

Now, we've looked at the science behind hangovers and ways to prevent them. But what if you've already crossed that bridge and are in the throes of a full-blown hangover? Fear not! Some home remedies can actually help alleviate your symptoms.

1. Hydration is key. Sip on water throughout the day to combat the dehydration caused by alcohol. Replenishing lost fluids can alleviate dehydration-associated symptoms such as thirst, fatigue, and headache.
2. Nutrient-rich foods. Choose foods that restore essential nutrients and minerals that alcohol may have depleted. Think bananas for potassium, eggs for cysteine, and whole grains for B-vitamins. 
3. Ginger tea to the rescue. Ginger is known for its anti-nausea properties — brewing a fresh cup can help settle your stomach.
4. Get moving (Gently). A gentle walk outside can boost endorphins and might help clear your head. But remember: this isn't the time for high-intensity workouts! 
5. Sleep it off. If you're feeling awful, sometimes the best remedy is a little more shut-eye. Rest can help your body recover! 
6. Toast and honey. Honey on toast can be a gentle way to reintroduce food to your stomach and can also help regulate blood sugar levels. 
7. Electrolyte solutions. Sports drinks or rehydration solutions can alleviate hangover symptoms by restoring electrolytes, balancing fluids, and boosting hydration.

Summing Up

Being proactive can greatly reduce your chances of waking up with that dreaded hangover. But again, the surefire way to prevent a hangover is to moderate your intake or opt out altogether. Your future self will thank you!

And if you're on a journey to cut back or quit, know that every step is a move towards a healthier, more vibrant you!