Those who answered with some of the earliest times were then asked whether they typically woke up by 5:30 a.m. It turned out that eight patients, or one out of every 300, did so. For five of those patients, this so-called advanced sleep phase was genetic, meaning they had multiple relatives who woke up extremely early, too.

Ptáček says his study is unique because it shows that advanced sleep phase “isn’t rare, and it’s only a problem if the person finds it undesirable.” He and his co-authors found that several advantages come with being an early riser. Extreme larks wake up more easily than others, and they don’t tend to sleep in on weekends, as many others do. They might even be healthier than people who are night owls: Late bedtimes are associated with some negative health consequences, such as Type 2 diabetes and heart disease.

Also in their favor, larks are more likely to benefit from the societal impression that people who wake up early are go-getters and people who wake up late are lazy. That’s not actually true; plenty of night owls wake at noon and work until 2 a.m., right as larks are getting up and brewing coffee. Nevertheless, the stereotype persists.

Being an extreme lark isn’t always blissful, though. Larks aren’t exactly the life of the party: They tend to go to bed by 8:30 p.m., the Sleep study found. Sabra Margaret Abbott, a neurologist at Northwestern University who wasn’t involved with the study, explains that some patients might find that their natural sleep window happens from 7 p.m. to 3 a.m., but they are rarely able to go to bed before 10 p.m. because of work and family obligations. “They will still not be able to sleep past 3 a.m., but will then be sleep deprived the following day,” she told me via email.

Abbott added that if you are someone who finds your natural sleep rhythms undesirable, you can try to adjust them by taking melatonin, a sleep hormone, and using “strategically timed light.”

Ptáček told me that the 69-year-old woman he met 20 years ago was unhappy with her early-rising nature. She would wake up when it was still cold and dark, and when no one else was awake yet. She grew depressed. Sometimes, she would vacuum at 4 a.m. just to fill the time. One of her relatives, meanwhile, was a very successful businessman who loved his advanced sleep phase. “He felt virtuous for getting up early,” Ptáček said. He thrived on exercising at a 24-hour gym at 3:30 or 4 in the morning.

There are some limits to this study. Since Ptáček and Jones ran their study at a sleep clinic, most of the patients had sleep apnea. Ptáček said he found that the presence or absence of sleep apnea does not affect whether someone will be a lark or a night owl, but Abbott and other experts I asked were not so sure that the data are perfectly generalizable to the general population. Also, the overall number of patients with advanced sleep phase was quite small—just eight total—which would make extrapolating patterns outside of this sample even harder.

Even so, part of the study’s goal, Ptáček told me, was to make people think “about the fact that we’re all different, and our genetics are defining, in part, who we are. And what’s good for you may be different from what’s good for me. People tend to compare everything against the average, but … we can’t impose the average on everybody.”