This article originally appeared on Tonic.
You might have noticed that with each passing birthday, your ability to bounce back after a night of debauchery seems to be getting more and more difficult. One moment you can rage all night, maybe even go for a run the next day with alcohol still circulating through your veins. The next, you can barely open your eyes the morning after throwing back a few gin and tonics. Someone would have to pay you to go on that run.
Blaming your maturing body for this, um, downgrade might seem like a cop out, but it's actually a valid excuse. While there hasn't been a lot of research on why drinking seems to be harder on the body as the years go by, there are a few theories.
"One hypothesis is that we have fewer liver enzymes or that these enzymes do not work as efficiently the older we get," says George Koob, director of the National Institute on Alcohol Abuse and Alcoholism. "Enzymes are responsible for metabolizing alcohol to help clear it out of our system, so this could mean it ends up being in the body for a longer time, thus prolonging a hangover." One study found that as mice got older, they had less glutathione, an antioxidant that helps detoxify alcohol. It's possible—but not certain—that something similar happens in people.
But it's not just the liver. As the years add up, our bodies change in ways that impact how alcohol is processed. "Older individuals have less total body water thereby decreasing the volume in which substances, such as alcohol, can circulate," says Stephanie Yarnell, a fellow at the Yale School of Medicine. "This can lead to a higher blood alcohol concentration."
There's also the brain, which isn't immune to aging either. "I think of a hangover as a mini withdrawal symptom," Koob says. "When you're younger, you have more brain plasticity which allows you to recover more quickly. This means that your withdrawal period is shorter. But as you get older, the brain can lose some of this plasticity, leading to a longer withdrawal."
On top of all that, people also tend to take more medications as they get older, and mixing meds and alcohol can get murky, Koob says. "Antacids like ranitidine and cimetidine can potentially increase one's blood alcohol concentration, and booze could amplify the side effects of sedatives," he says. Either way, you'll end up feeling crummier. (Quick PSA: If you're taking any medications, it's always best to check in with your doctor about how drinking affects them.)
Koob says that the NIAAA plans to look into how age impacts the body's response to alcohol given that there is not much data on the topic. However, studies have found that getting older adults to participate in research is a challenge because they tend to be less trusting and may be less open to others probing into their lifestyle.
It'd be worthwhile, though, given that drinking is not something people seem to ditch after their 20s: The most recent Gallup poll found that 67 percent of Americans 18 to 34 years old drink alcohol, and 72 percent people 35 to 54 years old drink. While the research catches up, you can continue to confidently blame your age for your increasing desire to draw the shades and pop two Advil after a long night.