(Redorbit) - If you wake up confused, groggy, and with a headache tomorrow after drinking only a couple of glasses of New Year’s party wine, it may be because you got more than you bargained for.

According to a new study from University of California researchers, wine bottles tend to contain more alcohol than what is listed on labels. More specifically, the study revealed that Chilean and Spanish red wines had the greatest discrepancy between what was on the bottle and what the wine contained. Chilean and American whites also had large discrepancies.

Although the difference between labeled and actual alcohol content was just on average 0.42 percent higher than stated on the label, the study team said this is a significant difference.

“A discrepancy of 0.4 percentage points might not seem large relative to an actual value of 13.6 percent alcohol by volume, but even errors of this magnitude could lead consumers to underestimate the amount of alcohol they have consumed in ways that could have some consequences for their health and driving safety,” study author Julian Alston, an economics professor at UC Davis, told The Telegraph.

“In particular instances the discrepancies could be much larger than average,” Alston continued. “An average error of 0.4 percentage points is much more significant compared with the typical range for wines in a particular category, for instance, Napa Valley Cabernet might be expected to have alcohol content within the range of 13.5–14.5 per cent alcohol by volume, and an average error of 0.4 percentage points is large in the context of this range."

The study team said they discovered a propensity to overstate the alcohol content for wine containing a fairly low percentage of actual alcohol, and a propensity to understate the alcohol content for wine containing fairly high alcohol content.

People want stronger wine

The scientists also said, generally speaking, the percentage of wines across the planet has climbed by an average of two percentage points during the past 18 years. At the outset of the study, the team theorized that global warming may be accountable, but after matching information to climate models across the planet they discovered only a small link. They also noted a developing trend for stronger wines.

“Discrepancies between label claims and actual alcohol content of wine suggests that in many places the rise in alcohol content of wine is a nuisance consequence of choices made by producers in response to evolving demand for wine having more intense, riper flavors,” Alston said.