Here’s How Your Saturday Morning Hangover Actually Changes Your Brain

by JR Thorpe
Attractive brunette sitting on bed with headache

Humans have likely been experiencing hangovers — that charming mixture of nausea, headaches, light sensitivity, cognitive issues and other symptoms — since alcohol was first created for our consumption nearly 10,000 years ago. However, just because the morning after the night before has a long history, doesn't mean we understand it fully. "We don’t really know what causes hangover per se," Dr. Robert Swift, Professor of Psychiatry and Human Behavior at Brown University and a leading researcher on the pharmacology of alcohol, tells Bustle. "There’s still different theories about what causes it." The answer, it appears, may lie in the brain — and what happens in the brain when you're hungover is more fascinating and controversial than you might think.

The impact of hangovers on brain function is complicated. Dr. Sally Adams, an assistant professor in health psychology at the University of Bath, tells Bustle that her research shows that the day after heavy drinking, people experience problems with "short and long-term memory, sustained attention and psychomotor skills," and that decision-making, impulse control and emotional processing also suffer. Many parts of neurological function are involved in a hangover, from hormones and neurotransmitters to the brain's electrical activity. Here's what we do know about what your brain looks like when you're hungover — and how intense the neurological impact of excessive drinking really is.


Your Brain Becomes Over-Excited

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Alcohol is a depressant, explains Dr. Swift, and there's a theory that hangovers might be explained by the body going into mild alcohol withdrawal after it's processed. "Alcohol is a sedative in high concentrations, and it depresses the brain," he tells Bustle. "When the alcohol is metabolized and disappears, the brain, which has been depressed, rebounds and is over-excited."

This over-excitement is shown in various ways. Alcohol has a chain reaction on two of the most important neurotransmitters in your brain. Glutamate, Dr. Swift says, is "the major excitatory neurotransmitter in the brain", and alcohol stops it working so well. When the alcohol's effects wear off, glutamate receptors over-react as a response.

The other neurotransmitter that's affected is GABA, or gamma-aminobutyric acid. Dr. Adams tells Bustle that GABA is a "major inhibitory neurotransmitter"; in other words, it tends to regulate activity in the brain. After you drink, she says, "the body decreases the number and sensitivity of GABA receptors." The result: a more active brain.

This over-excitement shows up in the brain's electrical activity too. "Even though a person may feel fatigued, their brain is actually excited and over-active," says Dr. Swift. The over-stimulation may be the reason why some people with hangovers are sensitive to light and sound.


Alcohol Interferes With The Brain's Hormone Production — And Makes You Thirsty

The major reason you're dehydrated during your hangover, says Dr. Swift, is down to alcohol's effects on another part of the brain. Vasopressin is an anti-diuretic hormone that's synthesized in a particular part of the brain, but alcohol inhibits its production — with the consequence that you urinate more. "Alcohol makes you urinate out more than you consume," Dr Swift tells Bustle. Hence your dry mouth and aching head.


The Brain Has Higher Dopamine Levels, Which Can Create Nausea

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Surprisingly, it's not exactly known why people experience nausea when they're hungover, Dr. Swift says. However, there's a sound theory about it. "Alcohol does release dopamine, and dopamine can be a stimulant for vomiting," he explains, noting that medications that boost dopamine in Parkinson's disease patients are also known to cause vomiting — and that if you take a dopamine blocker, it's known to help nausea.

Dopamine itself is a neurotransmitter that plays a key role in the brain's reward circuitry, and it's a big reason why drinking alcohol is so pleasurable; a study in 2013 found that even a taste of alcohol will induce the brain to release dopamine.


Your Brain Can Experience Higher Inflammation Levels

A hungover brain isn't a happy brain — and part of the reason, Dr. Swift says, is that it may be experiencing some immune system issues. "In the brain, there are immune system cells called microglia," he tells Bustle. "Inflammatory things activate microglia in the brain, increasing inflammation. Alcohol activates them and causes them to release inflammatory cytokines." That raises the overall inflammation levels in the brain, and may contribute to the flu-like symptoms of a hangover.

Some research indicates that the microbiome in the intestines might send inflammatory compounds to the brain when you're hungover, too. If these compounds get into the bloodstream, says Dr. Swift, "they can produce inflammation and, if they get into the brain, can activate the microglia." Result: higher inflammation levels and a grumpy brain.


The Brain's Biological Clock Is Skewed

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If you're hungover, you're likely sleepy and not exactly as alert as you could be. This is down to two separate neurological issues, says Dr. Swift. One is that the body has an innate clock that tells it when to wake and sleep, controlled by an area of the brain called the superchiasmatic nucleus, and we know that alcohol interferes with it.

The other is less about how much you drink and more about when you drank it. "If you stay up way past your bedtime drinking, it’s kind of like jet lag," Dr. Swift tells Bustle. "Your biological clock is going to be off because you didn’t go to sleep when you were supposed to." It seems that alcohol consumption isn't quite like jet lag, because alcohol doesn't affect the sleep hormone melatonin, but it's enough to make your brain's clock feel slightly off.


Unfortunately, the complexity of hangovers means that there's no one catch-all cure for them – aside, Dr Swift says, from not drinking at all. "If there were something, we wouldn’t still be looking for new hangover cures," he says. However, next time you lie in bed clutching your aching brain, you can be comforted by the fact that no matter how complicated the hangover process is, it's all temporary.