In 2016, a study of nearly 90,000 people appeared to suggest that humans could be genetically predisposed to being either an early bird or a night owl. The study—which was conducted by scientists at 23andMe, a genomics company best known for their at-home ancestry test kits—found that genetics do in fact contribute to whether we self-identify as a morning or evening person.
But they also said that genes are only a small part of what actually determines your sleep patterns. “Ninety percent of what contributes to whether you’re a morning or evening person is something other than the genetic differences between people,” says David Hinds, 23andMe's principal scientist. Hinds says age and gender also play a role. Of the nearly 90,000 people who participated in their survey, older people and women identified as morning people more than younger people and men did.
It’s difficult to get a straight answer to the question of whether or not our sleep preferences are predetermined because there are so many factors that play a role—genetics, biology, environment, lifestyle, even our mental health.
Cristoph Randler, a chronobiology researcher who has authored dozens of articles about the study of biological rhythms, believes that the preference for being up early is about 30 to 50 percent predetermined. “Some people are really flexible and can shift their sleep timing, while others seem unable to do this,” Randler says.
In other words, an early rising routine is not necessarily impossible for those who don’t naturally prefer the mornings, but it might be more challenging for some than others. And here’s another twist: Though modern humans in the west have relatively uniform work hours and culturally agreed upon norms for sleeping and waking times, evolutionary scientists believe humans may have evolved to keep a wide variety of sleep schedules.
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Evolutionary scientists look to the hunter-gatherer Hadza people of Tanzania, for instance, who have generously agreed to be studied for clues about how early humans may have lived. A study of their nighttime activity found that not only did individual sleep rhythms vary widely, there were typically several people awake at any given time.
These findings support the Sentinel hypothesis, a theory of human sleep first proposed in the 1960s that said human groups may require at least some members to stay awake during sleep times, to keep watch for external threats. Knowing that another group member was awake allowed those sleeping to get deep, restful sleep, which improves brain function and a host of other health outcomes—surely an evolutionary advantage. In other words, staying up all night probably had a specific and vital function for our early ancestors, and that doesn’t go away just because your boss wants you at your desk by 8 am sharp.
But in the same way that having the genetic makeup of a morning person doesn’t necessarily mean that you will be one, the Sentinel hypothesis—even if evidence continues to prove it to be true—doesn’t mean you’re powerless over your sleep habits. Aspiring early risers can make some tweaks to their lifestyle to make the shift easier. Though they may not agree on much else when it comes to sleep patterns, experts do agree that sunlight is one of the most significant cues that keeps the circadian clock in check.
“The most potent driver of our circadian system is light. A night owl wishing to be a morning person would want reduced light exposure at night, and a lot of light in the morning,” says Jeffrey Ellenbogen, a physician and researcher of neurophysiology of sleep at Johns Hopkins University. Ellenbogen’s advice includes the light from electronics, so yes, if you’re trying to wind down earlier, put your phone, tablet, and laptop away. And though often ill-advised, it might not be a bad idea to reach for your phone first thing in the morning, especially if you’re trying to wake up before sunrise.
The circadian rhythm responds to other cues, too, which means you can create cues solely for the purpose of hacking your sleep cycle. "One reason bedtime rituals are so commonly used with babies and children is that baths, teeth brushing, and bedtime stories are essentially a series of cues to help their bodies transition into sleeping mode," says Charles Hattman, a psychotherapist and licensed professional counselor at Onward Behavioral Health in Philadelphia. Even if you don’t have someone to read you a story, sing you a song, or tuck you into bed at night anymore, you may be able to achieve a similar effect by making yourself a cup of tea, or diffusing some oils before bed, for instance.
As with any habit change, consistency is key: “Make the changes slowly, over days or weeks, and then stick with them for maximum effect. It takes discipline, but can be done,” Ellenbogen says. While some research has suggested that early birds have better health, it’s still largely unclear whether waking up early is the cause of better health or the result of it. So if you’ve given it your best shot and just can’t get accustomed to an early morning wake up, it’s probably not that important. And definitely not worth losing sleep over.
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