There’s plenty of data that gives restaurant operators insight into the drinking habits of the people who frequent their bars. But a new study conducted on behalf of a hangover cure provider offers a unique perspective on the topic. In particular, it explains why your otherwise-talented cooks and servers occasionally have really, really bad days at work

Rally Labs—the makers of Blowfish for Hangovers, an effervescent-style over-the-counter hangover remedy—bankrolled the study. The company hired a third-party research firm to query 5,249 alcoholic beverage drinkers over the age of 21. Those findings were then paired with alcoholic beverage sales data provided by the Alcohol Epidemiologic Data System and additional beverage industry sources.

The study turned up numerous data points that give operators insight into the behavior of their restaurant’s bar customers. But we before we examine them, let’s look first at what the study found to be the professions in which workers are most likely to be hung over while on the job.

The top five:

1. Waiters

2. Realtors

3. Salespeople

4. Police officers

5. Chefs

Workers who become hung over can bag the day and simply call in sick; nineteen percent do. But most show up, although not necessarily on time. Twenty-eight percent of survey respondents said they have been late to work because they were hung over. Overall, 51 percent said they have been hung over at work.

The customer service implications of this latter number are clear.  Hung over employees typically feel lousy and are primarily interested in trying to make it to the end of their shift.  They can only give you and your customers the bare minimum effort. There’s not much an operator can do about it, although it may be wise to dispense aspirin or a hangover remedy like Blowfish in obvious cases. But at least be aware of what’s going on and adjust accordingly.

Here are some drinking statistics the Blowfish for Hangovers study turned up:

* People drink more often than they admit. Respondents to the Blowfish study said they had, on average, 277 drinks per year. People actually consume 819 drinks per year.

• America’s top three drinks are beer, vodka and red wine.

• The top three drinks for producing hangovers are tequila, vodka and red wine.

• The country’s favorite beers, according to survey respondents: Blue Moon, Sam Adams and Bud Light.

• The drink of choice for women: the margarita; for men, rum and Coke.

• The shot of choice for women: the lemon drop; for men, the Jagerbomb.

Keep these broad preferences in mind the next time you’re trying to come up with new happy hour specials or signature drinks for your bar. And keep an eye on your harder-partying employees; there’s a reason they may be feeling a little fuzzy at the start of their shift.