But here's what we learned about them this year anyway.
So, you said goodbye to 2015 with about a gallon of vodka and beer. Congratulations, you played yourself, and now you're enjoying your first hangover of the year.
You might be thinking, surely science has by now come up with a way to "cure" the ailment that has plagued humans since the first person to ferment a bunch of grapes? Maybe some kind of a pill, or that crazy morning-after saline drip thing that rich people are getting really into?
Unfortunately, no. You're fucked. This is because hangovers are kind of a mystery. The diverse constellation of symptoms that we call "hangovers" are a chronically understudied phenomenon, although groups like the Alcohol Hangover Research Group (AHRG) are trying to change that.
The studies that have been done show that hangover symptoms are likely the combined result of many factors associated with alcohol consumption—it dehydrates you, disrupts sleep, and is partly metabolized into a highly reactive compound called acetaldehyde that can be toxic to the body. In high enough concentrations, it can lead to sweating, nausea, and other nasty hangover symptoms.
Researchers have also noticed high levels of molecules called cytokines in people with hangovers. These molecules are used by the immune system to communicate, which has led some researchers to the hypothesis that hangovers are inflammatory responses by your immune system, like when you get an infection.
Basically, there's no single explanation for what causes a hangover, and no single cure—yet. But scientists are continuing to research the root causes of our hangovers, and how to cure them. Here's what we learned about hangovers in 2015.
ASIAN PEARS ARE YOUR FRIEND
This one really comes down to your decisions the night before. You know, before you start drinking.
According to a study by researchers at the Australian Commonwealth Scientific and Industrial Research Organisation, ingesting the juice of Asian pears, also known as nashi pears, could mitigate some hangover symptoms like memory loss and sensitivity to light. The catch is that you have to do it before you drink.
In their study, they fed participants 220 milliliters of pear juice before consuming alcohol. "In particular, reductions were seen in blood acetaldehyde levels, the toxic metabolic thought to be responsible for the hangover symptoms, with pear juice consumption," lead researcher Manny Noakes told the Sydney Morning Herald in August.
Another small study from the National Institutes for Health found that drinking Korean pear juice before consuming alcohol can reduce overall hangover severity, reduces memory loss, improves concentration, and reduces levels of acetaldehyde in the body.
SOME FOLK REMEDIES MIGHT ACTUALLY WORK
Pear juice wasn't the only natural hangover remedy that got some scientific scrutiny in 2015 and came out a winner.
A study published in Natural Product Sciences, a publication of the Korean Society of Pharmacognosy, found that a combination of extracts from various plants reduced hangover-causing metabolites in rats. These plants included kudzu, sometimes called Japanese arrowroot, and Sorbus commixta, or Japanese rowan. Previous research suggests that kudzu can reduce acetaldehyde, and Sorbus commixta has anti-inflammatory properties.
When administered to rats, a 200 millimetre dose of a mixture of plant extracts reduced acetaldehyde levels by just over 11 percent compared to a control group. Again, acetaldehyde is the potentially toxic metabolite leftover by alcohol that researchers believe can cause hangover symptoms in humans.
Another group of South Korean researchers published their findings about the efficacy of Acanthopanax senticosus (sometimes incorrectly called "Siberian ginseng") in the journal Die Pharmazie. According to the researchers, doses of plant extracts resulted in a significant reduction in hangover symptoms in subjects, which they attribute to the plant's anti-inflammatory properties, lending credence to the idea that a hangover is an inflammatory response by the body.
STILL NO CURE
This is, unfortunately, the sad reality of the hangover: if you have one, you're already screwed.
While some natural remedies may help, they only treat parts of what makes having a hangover a living hell—there's no total "cure," except for not drinking.
Researchers discovered as much when they polled nearly 2,000 Dutch and Canadian students about their drinking habits and hangover avoidance strategies. Two main findings came of this: drinking water before you go to bed probably doesn't do too much to help you in the morning, and the only students who successfully avoided hangover symptoms were the ones who didn't drink enough to get drunk.
"The more you drink, the more likely you are to get a hangover," lead author Dr. Joris Verster, a member of AHRG, told the BBC in August. "Drinking water may help against thirst and a dry mouth, but it will not take away the misery, the headache and the nausea."
Science still has a long way to go before there's a little pill that can make the pain go away. So, what can you do right now?
The best person to take advice from on this topic is probably one of the foremost researchers pushing the study of hangovers, Richard Stephens, a psychologist at Keele University in the UK and a member of AHRG. He told the Atlantic in an interview last year that when he drinks too much, he has a big fried breakfast the morning after, just like the rest of us non-scientist types. This is because a meal full of potatoes, bread, and other foods loaded with carbohydrates can help to replenish sugar levels in your body.
Alcohol inhibits the liver's ability to release glucose into the bloodstream, resulting in what's known as a hypoglycemic effect—low blood sugar. And although it may sound a bit strange, you should consider washing it all down with some soda. According to one 2013 study that looked at liquid hangover treatments, Sprite-like soft drinks are the most effective at reducing acetaldehyde in the body thanks to a common additive: taurine.
Chill out, eat up, and, I don't know, take a nap or something. Happy New Year.