It’s Friday. If you feel like putting an exclamation point at the end of the previous sentence, you’re not alone.According to a new study by sociologists at Cornell University that sampled 2 million people in 84 countries, there is a global biological rhythm that sees our happiness levels peak at the end of the week and over the weekend. And while Sunday is the day that sees the most overall positivity, Monday sees the least. Sounds about right, no?But the weirdest part is that even in countries where Saturday and Sunday are not the weekend, the stats held true. “This is a significant finding because one explanation out there for the pattern was just that people hate going to work. But, if that were the case, the pattern should be different on the weekends, and it’s not. That suggests that something more fundamental is driving this—that it’s due to biological or circadian factors,” one of the study’s authors Mr. Scott Golder told The New York Times.The daily rhythm the sociologists uncovered held true across all seven days of the week. While people typically wake up on the wrong side of the bed, once they get some breakfast, their mood lightens up. Although the perk slowly declines into the late afternoon (when many folks start diving into their afternoon latte), people cheer back up before bedtime.After all, how can you not smile when you’re in your cozy pajamas? (Maybe there’s even more reason to be happy if you sleep naked!)QUIZ: How Happy Are You?The researchers determined this natural emotional rollercoaster by tracking Twitter. Using specialized software they analyzed 500 million public tweets, combing them for positive buzzwords and emoticons like “awesome” and “:)” as well as negative terms like “annoy” and “afraid.”Critics argue that while a bevy of new data is available at researchers’ fingertips thanks to the internet and social media, the samples really only come from people belonging to an affluent economic bracket who can afford things like smartphones, iPads, and a computers. Not to mention, their average user age skews young. Plus, on a basic communication level, the software designed to analyze the samples in this study is only fluent in English and it also doesn’t speak human sarcasm. For instance, what if the computer reads “:P?”But while the study might not be proof, it does bring some welcomed good news as we head into these colder months. Supposedly, even as the weather takes a turn for the worse, our moods won’t. We’re all overall just as happy in the summer as we are in the winter—probably because we have Twitter to amuse us when we’re stuck indoors.MORE: What’s Your Online Image Saying About You?