On Friday, U.S. surgeon general Vivek Murthy suggested a major change in how America labels alcoholic drinks: booze should come with cigarette-style warnings, given that alcohol is a leading preventable cause of cancer, similar to the labeling Ireland is rolling out later this year. This has intensified focus on alcohol ahead of the scheduled update to the US Dietary Guidelines for Americans later this year, but it’s not clear if new labels should be expected—adding them would require action from Congress.

Drinkers, though, are already taking their own action. If the bars look a bit emptier this month, it may be because more people are trading happy hour for Dry January. The tradition, in which people abstain from alcohol for the entire month, is growing in popularity.

According to data from the polling organization CivicScience, one in four US adults completed Dry January in 2024, up from 16 percent the year before. And an estimated 15.5 million people in the UK, where the movement originated 12 years ago, said they planned to participate this year, according to Alcohol Change UK, the charity behind the movement. In 2013, that number was just 4,000. Temporary sobriety is contagious, and studies show that pushing away the bottle for a month does have immediate health benefits. But whether the health benefits last—or reach those most in need—remains unclear.

“This concept, that it’s a one-month detox or spring clean that gets you ready for the rest of the year, I don’t think there’s any evidence for that,” says Gautam Mehta, an associate professor in hepatology at University College London who has studied the effects of month-long sobriety. “But people do seem to get more of an understanding with their own relationship with alcohol and what they want to do with their relationship with drinking for the rest of the year.”

A 2018 study Mehta worked on followed a group of moderate drinkers who went sober for a month and compared them to a control group that kept up their old habits. The most noticeable benefits for the nondrinkers included better sleep and weight loss. They also experienced more subtle effects; their blood pressure fell and their biomarkers for insulin resistance improved, an indicator of decreased risk for developing diabetes.

And some people say a sober month does help them to cut back overall. In 2019, University of Sussex researchers analyzed a survey filled out by several thousand people. They found that 59 percent of respondents reported drinking less six months after Dry January, and 32 percent said they were in better physical health. However, only about 38 percent of people who began the survey followed up at the six-month mark.

Still, taking only a short break doesn’t necessarily give the body time to fully recover from the effects of drinking. That’s what two British doctors, who are also identical twins, showed when they carried out their own experiment in 2015. (Mehta provided expertise in the experiment, which aired as an episode of BBC’s Horizon.) They each spent one month sober, and tests showed they had identical healthy livers. Then, they spent a month drinking 21 units of alcohol weekly, the recommended limit for men in the UK at the time (it has since been revised down to 14 units). There was a difference in how they got the job done: One drank three units (about one large glass of wine) every day for a month, and the other drank only once a week, but binged all 21 units. At the end of the month, both had increased liver inflammation. For the binging twin, it was clear that even taking six days off between binges wasn’t enough time for the organ to fully heal.

Short periods of abstinence also won’t prevent drinkers from increasing their cancer risk. For at least four cancers—mouth, upper throat and voicebox, oesophageal, and breast—any consumption of alcohol raises the risk, though keeping to recommended limits can keep the risk of these cancers low, says Alcohol Change UK. And participating in Dry January can help people work towards this. Another study from the University of Sussex researchers found that just 11 percent of people who tried Dry January had a rebound in drinking and consumed more alcohol than they did before. However, those who failed to complete the full month were more likely to drink more afterward than those who made it through the 31 days.

Dry January may be successful because it’s a challenge posed to moderate drinkers—those who drink heavily could experience withdrawal if they decide to suddenly stop without professional supervision. And its participants are self-selecting; they engage with the movement because they want to limit alcohol or rework their relationship with it. If they feel the benefits, they may be more likely to keep cutting back while now having the skills to turn down alcohol. “People who are actually at the least risk are the best catered to with Dry January and other campaigns, whereas people who really do have a problem seem to be missing out in terms of attention and resources,” says Ian Hamilton, an honorary fellow in addiction at the University of York.

Overall, drinking habits are waning, thanks in part to the rise of non-alcoholic adult beverages. Polling from Gallup has found that the average number of alcoholic drinks Americans consume each week has slowly fallen since the turn of the century. Averages, though, can conceal how behaviors vary across the population, since many people don’t drink at all, and a small percentage of people consume heavily, reaching more than 10 drinks a day.

Hamilton says there should be more long-term research on Dry January’s effects—and that would mean following participants for six months to a year. With millions of people taking part, there’s still much to learn about how significant the benefits are and how long they last for different groups, based on how much people drink and their diet and exercise choices.

One thing is clear: Putting alcohol on hold for 31 days and then coming back to the bar for rounds of shots isn’t life-changing. But what people learn about themselves and how drinking affects them physically could be. “Some people unfortunately view Dry January as the job done,” Hamilton says. “I’d rather exchange Dry January for people doing a more regular period of abstinence.”