A favorite trope of sleep research is to divide the entire human population into two cute, feathered categories: early birds (also called larks) and night owls. Often, these studies link people’s natural sleep patterns—called their chronotype—with some waking behavior or personality trait.
It doesn’t take long to see which team more often comes out on top. (Hint: it’s the one that catches the worm.) Research says that early birds are happier, more punctual, do better in school, and share more conservative morals. Night owls are more impulsive, angry, and likely to become cyberbullies; they have shoddier diets and, most critically, are worse at kicking soccer balls.
But can the population really be categorized so neatly? Or is the research painting an incomplete and overly moralistic picture?
A study published May 24 in PLOS ONE by a group of Polish researchers takes a fresh look at the long-established link between being an early riser and being conscientious by examining a separate but potentially important variable that might underlie the link: being religious. The team found that people who woke up earlier tended to score higher on all dimensions of religiosity, leading them to conclude that being religious could help explain why early risers are more conscientious and more satisfied overall. “Morningness” might be closely aligned with godliness, in part because certain religions practice early-morning prayer—so religion could be driving the link between rising early and being conscientiousness.
Religion, of course, is just one under-examined variable that may be contributing to the link between sleep and waking behavior. Countless more exist—which suggests we’re probably thinking about the morning bird/night owl divide too starkly, in research and in real life. “I think most people would recognize that, in reality, [chronotype is] more of a continuous type of variable,” says Brian Gunia, a sleep researcher, professor, and associate dean at Johns Hopkins’ Carey Business School. It exists on a spectrum: not everyone is always one or the other. But so much research uses this binary classification because people are usually able to self-identify that way, Gunia says.
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The bias that people who rise early are morally superior to evening people doesn’t just loom large in scientific research. It’s at the very heart of the U.S.’s founding principles of industry and hard work, says Declan Gilmer, a PhD student at the University of Connecticut who studies workplace psychology. “If someone gets up at 6 a.m., and they show up at work early, they’re viewed potentially as more committed,” he says.
For his 2018 masters’ thesis, Gilmer asked people to imagine themselves as managers and review employees’ requests for easily accommodatable schedule changes based on a number of factors. He found that people acting as managers rarely treated chronotype-related scheduling requests—like asking to start and end the workday later when such a schedule didn’t interfere with meetings—as legitimate. And when night-owl employees made such requests, they viewed them much more negatively, even when they were just as productive as the early birds. Other recent research published in the journal Behavioral Sleep Medicine found that people “perceived night owls as significantly more lazy, unhealthy, undisciplined, immature, creative, and young,” the study authors write.
Yet a person’s sleep preference is far from fixed. Though it does have biological and genetic roots and “doesn’t vary from month to month or season to season,” says Fogel, “we know age is really important.” Chronotype can shift as you get older, he says, which means that research needs to control for things like age. “Some of the better work in the topic area has been trying to identify the genes that are most tightly linked to morningness and eveningness,” he says—genes that, if understood, could open the door to a more nuanced view of the topic.
Perhaps the most important reason not to rely too heavily on the “research-backed” moral superiority of morning birds is that aspects of your personality (like how hopeful and creative you are) and your own physiology (like how focused you are) that are supposedly linked to your chronotype change throughout the day. Very few chronotype studies include information about the time of day during which the research was conducted, but Gunia’s research has found that this seemingly simple factor can change data a fair bit. In a 2014 study of chronotype and ethical behavior, for example, “we found that morning people are most ethical in the morning, and evening people are most ethical in the evening, so maybe it’s more of a fit between chronotype and time [of day] than it is this idea that morning people are better or worse,” Gunia says. Studies that don’t take time of day into account “are missing half the equation.”
Humans don’t always fit neatly into one of two categories, even when it comes to their sleep preferences. As researchers work toward a more individualized view, just remember: You don’t have to be a morning lark or a night owl. You can be any kind of bird you like—there are plenty of worms to go around.