You’re not imagining it: Some mornings after parties are worse than others—even if you drink the same amount.
Hangovers, or veisalgia, as scientists refer to it, are our body’s way of telling us that we’ve overindulged on alcohol. Scientists aren’t sure exactly why we get them, but they have a few ideas: “Addiction specialists have often noted that a hangover is technically a form of alcohol withdraw at its most benign,” Laura Veach, a counselor and professor of surgery at Wake Forest University, told the New York Times. Usually, hangovers start when the alcohol in our bloodstream begins to decrease, and hit their peak when we’ve reached zero.
Additionally, alcohol makes us urinate more than usual, which flushes out our usual electrolytes and leaves us dehydrated (assuming you’re not matching each drink with a glass of water). But what’s worse is the buildup of a chemical called acetaldehyde in our blood, which is a byproduct of processing alcohol. Acetaldehyde is much stronger than alcohol, and is responsible for excess sweating, nausea, and vomiting, according to Smithsonian. Because the body is already parched, there’s less water available to expel the extra acetaldehyde.
Dark congeners
The kind of alcohol you drink may have an effect on the severity of your hangover. All booze is fermented, which creates alcohol and other byproducts, like carbon dioxide (responsible for harmless bubbles), and chemicals called congeners, or fusil oil impurities, which are a type of alcohol our bodies can’t process and make us feel sick. These congeners are also responsible for some of the distinct tastes in darker drinks, like whiskey, red wine, or brandy. A 2006 Dutch study on college students found that darker alcohol with more congeners tend to cause worse hangovers. (It also found that liquors were more likely to cause hangovers than beer or wine, likely because liquor has higher alcohol concentrations.)
Cheaper drinks are more likely to have more congeners, too. As Gizmodo explains, congeners can be filtered out through the distilling process, but cheaper alcohol isn’t distilled more than a couple of times; higher-quality booze, like Tito’s vodka, is distilled six times.
Sweet, bubbly mixers
It also appears that carbonation can actually make you more drunk (and, presumably, give you worse hangovers). One 2007 study found that when participants drank vodka mixed with soda, their blood alcohol levels were higher than those who drank straight vodka (or vodka mixed with water). In this case, the researchers hypothesized that this was because the added drink volume from the bubbles caused the stomach to release its contents to the small intestine, where alcohol is absorbed into the blood stream, sooner. Another study found that people who drank flat Champagne had lower blood alcohol levels than those who drank it with its bubbles.
And sugar may also play a role in the rate of absorption. “Commonly used mixers, such as lemonade, contain high levels of glucose, which have been shown to affect gastric emptying and therefore alcohol absorption rates,” the authors of the 2007 study write.
However, both of these studies involved 21 and 12 participants respectively, which is too small to define a relationship between carbonation, sugars, and resulting drunkenness.
No real cure
The only real tried and true hangover cure is time—which is an annoying thought to have when you’re sick in bed the next day. But eventually, your body will rid itself of acetaldehyde, and you can replenish your water and salt supply with a good meal (like brunch. Just saying.)
To avoid hangovers, the obvious answer is don’t drink to excess, and keep drinking water throughout the night. But, if you plan on partying hard, you could try eating pears ahead of time. In 2015 Manny Noakes, a nutritionist at the Commonwealth Scientific and Industrial Research Organization in Australia, reported that in a small trial, people who drank Korean pear juice before drinking had less severe hangovers, and were specifically better at concentrating the next day. Although those results were not published in a peer-reviewed journal, it probably wouldn’t hurt to try.