Have you ever been frustrated that you just can’t seem to jump out of bed at 5 a.m. to get a workout in before sunrise when your friend or partner does it so easily? Same. I’ve spent most of my life trying to force a schedule that didn’t align with my natural rhythm. But luckily, it’s not just a lack of willpower and discipline; there’s a scientific excuse.
This tendency is related to your chronotype, your “physical and behavioral preference for earlier or later sleep timing,” according to Nature, and it’s influenced by factors like age and genetics. (You may have seen quizzes across the internet that assign you an animal based on your sleep habits. If you wake up early, you’re a lion, while if you stay up all night, you’re a wolf, etc.) But knowing whether you’re a lion, bear, wolf, or dolphin isn’t necessary—and quite honestly, a little gimmicky.
“It’s been a bit twisted from the scientific explanation,” says Michael Gradisar, PhD, sleep researcher and head of sleep science at Sleep Cycle. “If we have to use any animals, it would really be a night owl and a morning lark. But the simplest way to think about it is: are you an early type of person or a late type of person?” (Or neither, if you’re solidly in the middle.) Most people naturally know what category they fall in, Gradisar says. “If you’re not sure, simply measure your sleep when you are free to fall asleep and wake up when you want to, like on the weekends,” he says when you’re not going out to a late-night party or waking up with an alarm for work. If you’re data-driven, a sleep-tracking app like Sleep Cycle can help you identify your sleep patterns, too.
Knowing your chronotype does more than just ease your guilt; you can use it to your advantage. According to sleep researchers, aligning your day with your chronotype can improve your cognitive function and athletic performance. If you’re performing the wrong activity at a non-optimal time for your circadian rhythm, you could be missing out on benefits to your motor learning, attention, and working memory, too.
When we start to lean into our chronotype—instead of fighting against it—we thrive. No matter what your chronotype is, circadian rhythms follow a similar 24-hour pattern. You reach the lowest point in your energy during your sleep—this may fall around 4 or 5 a.m. for those with an average chronotype (not early or late). From there, “our alertness increases across the day with our underlying circadian rhythm,” Gradisar explains. It continues to grow until the direction changes again—our second dip, the dreaded afternoon slump. For normal chronotypes, this generally happens in the afternoon, like 2 or 3 p.m. For early risers, this dip may come around midday (say, 1 p.m.), and for night owls, around 4 or 5 p.m. “It can be really noticeable when people don’t get enough sleep,” says Gradisar, “or maybe when the coffee has worn off, and people are sitting down, and they have to pay attention.”
