Hangovers are miserable, and they happen all around us. Yet the causes of hangovers are widely misunderstood. For example, we often rely on water after a night of heavy drinking to prevent hangovers the next morning. But this assumes that dehydration from alcohol consumption is the primary cause of hangovers. This is 1/5 correct. Dehydration is actually just one of five main factors that cause hangovers. These other 4 causes are equally, if not, more important to understand if we'd like to prevent hangovers.
In this post, we break down 5 main causes of hangovers, and how alcohol triggers a cascade of biochemical reactions inside our body.
What is a hangover?
Simply put, a hangover is our body's reaction to drinking too much alcohol.
Hangovers develop as our blood alcohol concentration returns to zero; typically occurring the morning after a night of heaving drinking. Hangover is characterized by a feeling of general misery that can last more than 24h, and includes symptoms such as dizziness, loss of focus, nausea, sweating, anxiety, fatigue, dry mouth, and gastrointestinal distress. It gets worse the more we drink alcohol, when we drink on an empty stomach, and when we haven’t slept.
Ok, so what causes a hangover?
Cause 1: Acetaldehyde build-up
Alcohol undergoes two-step process of metabolism in our liver. First, our liver enzyme called alcohol dehydrogenase (ADH) converts alcohol into an intermediate metabolite called acetaldehyde through oxidation. Acetaldehyde is an extremely toxic substance that binds to proteins that results in cellular inflammation; causing effects like sweating, nausea, and vomiting. Sound familiar? Luckily, our body is equipped with more enzymes like aldehyde-dehydrogenase (ALDH) and glutathione that convert this toxic chemical into acetic acid that gets safely flushed out of our body. But when we drink too much alcohol, our enzymes can’t keep up, and acetaldehyde builds up, causing the toxic hangover effect.
Cause 2: Glutamate rebound and reduced sleep quality
Alcohol binds to GABA receptors in our brain and increases GABA production, an inhibitory neurotransmitters that causes relaxation, lowered inhibitions, slurred words and loss of motor control that are classic symptoms of drunkenness. This, in turn, suppresses the release of Glutamate, an excitatory neurotransmitter that increases brain activity and energy levels. This is why alcohol has a depressive effect that make us fall asleep easily at first. But the rebound effect is why sleep quality is decreased, and we often wake up tired with anxiety. Our body has to work overtime to increase glutamate levels.
Cause 3: Dehydration
Alcohol inhibits the secretion of vasopressin, a hormone that keeps us from urinating unintentionally. When this enzyme gets suppressed, water flushes down to our bladder (along with electrolytes) to be excreted. Increased urination quickly leads to dehydration. And as our body draws water from our brain to function, it leaves us feeling dizzy and nauseous.
Cause 4: Loss of electrolytes
Electrolytes are vital to our body's ability to maintain homeostasis. They regulate bodily fluid balance, oxygen delivery, myocardial function, acid-base balance, and neurological functions. Alcohol causes our body to lose electrolytes similar to the way it dehydrates our body. A mild to moderate electrolyte imbalance can cause headaches and cramping. And the electrolytes we lose while drinking alcohol can't be recuperated with water alone.
Cause 5: Gastritis
Gastritis refers to inflammation of stomach lining. Consuming alcohol causes our stomach to produce excess amounts of stomach acid, which in turn irritates and inflames our stomach. Severe inflammation leads to nausea, vomiting, diarrhea, and bloody stools.