Being hung over means you’re experiencing the physical and mental aftereffects of drinking too much alcohol. It’s a collection of symptoms, not just one feeling, and it typically sets in as your body finishes processing the alcohol from the night before. The most common signs include fatigue, headache, nausea, thirst, muscle aches, sensitivity to light and sound, anxiety, irritability, and difficulty concentrating.
What a Hangover Actually Feels Like
A hangover isn’t a single symptom. It’s a cluster that can hit you in different combinations depending on how much you drank, what you drank, and your individual body. The National Institute on Alcohol Abuse and Alcoholism lists the typical set: fatigue, weakness, thirst, headache, muscle aches, nausea, stomach pain, vertigo, sensitivity to light and sound, anxiety, irritability, sweating, and increased blood pressure.
Some people get hit hardest by the headache and nausea. Others barely feel sick to their stomach but can’t think straight, struggling with memory, concentration, and a general mental fog. You might also notice a fast heartbeat, shakiness, or a sense that the room is spinning when you stand up. The experience varies widely from person to person and even from one drinking session to the next.
Why Your Body Reacts This Way
Several things happen inside your body when you drink heavily, and no single one explains the whole hangover. Instead, multiple mechanisms stack on top of each other.
Alcohol is a diuretic, meaning it makes you urinate more than the volume of liquid you’re taking in. This leads to dehydration, which drives the thirst, dry mouth, headache, dizziness, and lightheadedness that define a classic hangover morning. Your electrolyte balance gets thrown off at the same time, contributing to muscle aches and general weakness.
Your liver processes alcohol at a steady rate of roughly one standard drink per hour. When you drink faster than that, the excess alcohol and its toxic byproducts build up. One of those byproducts, acetaldehyde, is significantly more toxic than alcohol itself. Drinks that are darker in color, like bourbon, brandy, red wine, cognac, and dark whiskey, contain higher levels of chemical compounds called congeners. These are byproducts of fermentation, and one of them, methanol, breaks down into formaldehyde and formic acid in your body. People who produce larger amounts of these breakdown products tend to feel worse the next day. Tequila is a notable exception among clear liquors, as it also runs high in congeners.
Alcohol also irritates the lining of your stomach and increases acid production, which explains the nausea, vomiting, and belly pain. And it triggers an inflammatory response throughout your body, similar to what happens when you’re fighting off an infection, leaving you achy and wiped out.
How Alcohol Wrecks Your Sleep
One of the sneakiest parts of a hangover is the sleep disruption. Alcohol has a sedative effect that might knock you out quickly, but the quality of sleep you get is significantly worse. It changes your overall sleep architecture: you may get slightly more deep sleep early in the night, but then experience rebound insomnia later. The second half of the night, when you’d normally get the most REM sleep (the restorative stage tied to memory, learning, and feeling rested), gets suppressed.
The more you drink, the stronger this withdrawal rebound becomes, leading to fragmented sleep, trouble staying asleep, and waking up groggy. Alcohol can also cause or worsen snoring and obstructive sleep apnea, further degrading sleep quality. This is why you can sleep for eight or nine hours after a night of heavy drinking and still wake up feeling like you barely slept at all.
When Hangovers Start and How Long They Last
Hangover symptoms generally begin once your blood alcohol level drops back toward zero. For most people, that means waking up the morning after drinking, though if you drank heavily into the early hours, symptoms might not peak until the afternoon. Since your liver clears about one drink per hour, a night involving eight drinks could mean your body is still processing alcohol well into the next day.
Most hangovers resolve within 24 hours. Milder ones may fade by midday. Severe ones, especially after binge drinking, can linger into the following evening or even the next morning. If symptoms like confusion, seizures, slow breathing, or vomiting that won’t stop appear, that’s not a hangover. That’s alcohol poisoning, which is a medical emergency.
What Makes Some Hangovers Worse
Several factors influence how bad a hangover hits. The obvious one is volume: more alcohol means more symptoms. But what you drink matters too. Dark liquors with high congener levels consistently produce worse hangovers than clear spirits like vodka or gin. Mixing dark liquors with sugary mixers can make the effects of congeners even more pronounced.
Drinking on an empty stomach speeds absorption, which means higher peak blood alcohol levels and a rougher morning. Your body size, genetics, hydration status going in, and how quickly you drank all play roles. Some people are genetically less efficient at breaking down acetaldehyde, which makes them more hangover-prone even at moderate amounts. Age matters too. The same amount of alcohol tends to produce worse hangovers as you get older, partly because your body composition shifts and your liver works less efficiently.
What Helps and What Doesn’t
There is no proven cure for a hangover. Time is the only thing that truly resolves it, because your body needs to finish metabolizing alcohol and its byproducts, then repair the damage. That said, you can ease the discomfort. Drinking water or electrolyte beverages helps counter dehydration. Eating bland, easy-to-digest food can settle your stomach and stabilize blood sugar, which drops after heavy drinking. Rest helps, though the sleep you get while hung over won’t be as restorative as normal sleep.
“Hair of the dog,” or drinking more alcohol the next morning, might temporarily dull symptoms, but it simply delays the hangover and adds more toxins for your body to process. Coffee can help with grogginess but may worsen dehydration and stomach irritation. Over-the-counter pain relievers can address headaches, though some are harder on your stomach and liver when alcohol is still in your system.
The only reliable way to prevent a hangover entirely is to drink less, or not at all. Spacing drinks out, alternating with water, eating before and during drinking, and sticking to lighter-colored spirits all reduce the odds of waking up miserable.