It's not always easy to predict how much you're going to drink when you go out — or how drunk you'll actually get. And according to a new study, your friends' drinking habits may have more of an effect on your own than you realize.For the study , published online this week in BMC Public Health, researchers surveyed and tested the breath alcohol concentration (BrAC) of 1,862 people who were out drinking. Of those, 400 participants went on to answer four questions about how drunk they felt, how much alcohol they'd had, and how dangerous they felt their drinking habits were.The researchers then ranked participants by their BrAC levels. They found that a participant's rank — whether he or she was simply more or less drunk than the others around — was much more strongly associated with that person's perceptions of his or her own drunkenness than with the actual BrAC amount. That suggests that even if your BrAC is high, you won't necessarily feel all that drunk if you're hanging out with someone who's drunker than you are. And if a few people in your crew are staying sober, those who are drinking may be less likely to overindulge."Researchers have historically worked under the assumption that those who drink [the] most alcohol incorrectly 'imagine' everyone else also drinks to excess," said Simon Moore, PhD, lead author on the study, in a press release . "[But] it turns out that, irrespective of how much someone has drunk, if they observe others who are more drunk than they are, they feel less at risk from drinking more."Of course, moderate drinking isn't usually anything to worry about. But drinking to excess has its risks , which become increasingly serious the more regularly you're overdoing it . So please appreciate the friends who tag along to the party but don't drink. They might just make your night — and the next morning — a lot more pleasant.