Individuals who tend to overindulge at holiday parties this season may want to choose their alcoholic beverages carefully to avoid feeling sick the next day. Researchers at Brown University say substances known as congeners affect the color, odor and taste of alcohol and can interfere with cell function and cause a hangover the morning after drinking.

According to Health.com, 95 study participants were served drinks containing either bourbon or vodka to gauge which alcohol caused a more severe hangover.

Researchers found that individuals who drank the bourbon drinks reported more severe hangovers than those who drank vodka. They say bourbon contains 37 times as many congeners as vodka.

A general rule of thumb when choosing hard liquors is that darker colored liquids have more congeners and may cause more day-after sickness. However, the same rule doesn’t hold true when it comes to wine and beer.

Scientists note that congeners aren’t the only factors that contribute to hangovers, as alcohol itself can cause feelings of sluggishness and pain.

The best way to avoid a hangover altogether is to avoid alcohol. For those who wish to enjoy an adult beverage, however, experts suggest alternating alcoholic drinks with water. Taking nutritional supplements containing vitamins C, B6 and B12 may also lessen the affects of a hangover.