In the collective imagination, night owls are free, creative spirits. Yet studies have shown that people who are more active at night face greater health risks. Do night owls experience more benefits or risks due to their rhythms? This Spotlight feature tackles this and related questions.

If, like Bram Stoker's famous character Dracula from the 1897 novel of the same title, you are most active when the moon is up and tend to go into hiding at sunrise, then you might not be a vampire, but you probably qualify as a night person or night owl.

Literature often romanticizes night owls. The fact that they keep unusual hours, and that they are most productive in the evenings or even at night can make them seem mysterious—both appealing and somewhat frightening.

"There is a romance about all who are abroad in the black hours, and with something of a thrill we try to guess their business," wrote Robert Louis Stevenson in Travels with a Donkey in the Cévennes (1879), his account of hiking in the French mountains.

Despite the romantic, mysterious image that books and movies might portray about night owls, many studies warn that people who frequently stay up until the early hours of the morning are placing their health and well-being at risk.

For instance, a 2018 study analyzing the relationship between bedtime habits and health in 433,268 adults found that night owls are more at risk of developing diabetes and are 10% more likely to die prematurely when compared with individuals who identified as morning people.

While few studies have analyzed what percentage of people among the world's populations are night owls, the research that does exist on this topic seems to suggest that a significant number of people do their best work in the evenings.

A study from 2011, which focused on college students in Saudi Arabia and worked with 540 male and 219 female participants, all aged between 18–32, found that 26.9% of the study participants were "evening types," who performed better later in the day. The study's authors also add that research conducted in Western countries indicates that an even higher number of college students qualify as night owls in Western societies.

Given the high number of people who are naturally inclined to go to bed late and wake up late, it is essential to understand what impact their rhythms may have on their health and why. In more general terms, research about individual body clocks and sleep-wake patterns can help us build a healthier and happier society.

In this Spotlight feature, we look at what makes a night owl a night owl, what other types there are, and how and why being a night or evening person impacts various aspects of health and well-being.

Circadian rhythms and chronotypes

"The morning was a wretched time of day for him. [...] On no morning of his life had he ever been in good spirits nor done any good before midday, nor ever had a happy idea, nor devised any pleasure for himself or others. By degrees during the afternoon he warmed and became alive, and only towards evening, on his good days, was he productive, active and sometimes, aglow with joy."

Thus goes the description, of Harry, a character in Herman Hesse's novel Steppenwolf, which first appeared in English in 1929. It is a good match for the daily patterns of night owls, who tend to be sluggish and unproductive in the mornings and become alert in the evenings.

But who is a night owl? To answer that question, we must first talk about body clocks. All humans—and other animals—have internal regulating mechanisms, or "body clocks," which allow a person to adapt to natural day or night cycles, "telling" them when to eat, rehydrate, have sex, and sleep.

As Dr. Roberto Manfredini—an expert in chronobiology and cardiovascular medicine from the University of Ferrara in Italy—and colleagues explain, "[t]he daily time-keeping system is called 'circadian' from the Latin 'circa diem,' which means 'approximately a day,' deriving from duration of a cycle of earth rotation."

However, not everyone's circadian rhythms coincide. Some people feel the most refreshed early in the morning, but feel like they're falling asleep by 9:00 p.m., and people who are most active in the evenings may have trouble waking up in the morning. As you've surely guessed by now, these are the so-called morning larks and night owls, respectively or, in more scientific terms, "morning types" and "evening types."

"The degree of morningness or eveningness is one of the most important aspects of individual differences in circadian rhythms, a phenotype known as chronotype," write the authors of a 2017 study featured in the journal Chronobiology International.

To find out whether a person is a morning type or an evening type, researchers typically use a test called the Horne-Ostberg Morningness-Eveningness Questionnaire, which assesses subjective preferences for activities throughout a 24-hour cycle.

More than 2 chronotypes?

The Morningness-Eveningness Questionnaire does not only distinguish between larks and owls; there is also a third option on this scale, namely the intermediate types, people who do not fully qualify either as morning or evening individuals. The "intermediate types," in fact, might be more widespread than either larks or owls.

"I'm a night owl and a morning bird. Generally, I'm fine both ends. I basically just don't get that much sleep," one person told Medical News Today.

Although most people fall in between the extremes of "morningness" and "eveningness," as a society, we don't have any terms to describe these other chronotypes. Or, more correctly, we didn't have any words until now. This year, a team of researchers from Belgium and Russia studied intermediate types in more detail, characterized them, and gave them names based on those characteristics.

The new study paper—published online ahead of print in the journal Personality and Individual Differences—identifies two additional chronotypes: "afternoon types" and "nappers."

"[M]orning types," the researchers write in their paper, are the "least sleepy in the morning and most sleepy in the beginning of the night while the opposite trend [is associated with] evening types." In addition, they explain, "[t]hose who might be named 'afternoon types' [are] least sleepy after the middle of the day and [...] more sleepy not only in the early morning but also at midnight, whereas those who might be named 'napper types' [follow an] opposite pattern characterized by 'afternoon dip' in combination with lower sleepiness levels both prior and after this dip."

Night owls: An endangered species?

But in a context in which the constructs of our global society accommodate morning lark habits—where "the early bird catches the worm"—it is night owls whose health is usually most at risk.

"[The] mismatch between a person's biological time and social time—which most of us have experienced in the form of jet lag—is a common issue for night owls trying to follow a normal working day," notes Elise Facer-Childs, PhD.

Formerly affiliated with the University of Birmingham in the United Kingdom, Facer-Childs currently works at Monash University in Melbourne, Australia. In a study published earlier this year, Facer-Childs and colleagues found that night owls experience something akin to jet lag every day. More precisely, connectivity was lower in certain brain regions of night owls than it was in morning larks. Essentially, this meant that evening types had shorter attention spans, slower reactions, and less energy than morning people.

An international review published in Advances in Nutrition in 2018 found that adults who fared better in the evenings were more at risk of developing heart disease, as well as type 2 diabetes. Its authors argue that "this may be potentially due to the poorer eating behavior and diet" in night owls.

Research from 2017 also shows that night owls are more likely to receive a diagnosis of obesity, which is a significant risk factor for conditions such as diabetes and cancer. This study's authors also suggest that "evening types" may have an increased cardiovascular risk. Finally, some studies suggest that night owls have an increased risk of depression when compared with morning larks.

Should owls turn into larks?

However, most researchers seem to agree that a great deal of these poor outcomes for physical health and mental well-being in the case of night owls may be because they are expected to function and be productive following a morning lark template, which does not suit them.

"A typical day might last from 9:00 a.m. to 5:00 p.m., but for a night owl, this could result in diminished performance during the morning, lower brain connectivity in regions linked to consciousness, and increased daytime sleepiness," notes Facer-Childs. "If, as a society, we could be more flexible about how we manage time, we could go a long way towards maximizing productivity and minimizing health risks," she adds.

At the same time, though, in a newly published study, Facer-Childs and team suggest that night owls might benefit by switching up their routine a little, by going to bed a couple of hours earlier than usual, and waking up a few hours earlier, too.

"We wanted to see if there were simple things people could do at home to solve this issue," says another one of the recent study's authors, Andrew Bagshaw, PhD.

The question of whether night owls should modify their rhythms to try and become "morning people," or whether workplaces should strive to accommodate the different needs of individuals remains highly contentious. Some people have indeed found that adjusting their routines so that they would become more active in the morning has actually helped them in the long run.

One person told MNT: "I used to be a night owl, and I converted. I used to stay up until 1:00 or 2:00 in the morning and then struggle to get to work on time. Then I decided I wanted to be a writer, so I forced myself to get up early to write before I went to work. Slowly, I converted myself into a morning person." He also added that now he has become more productive and he does not regret the switch.

Not a black and white issue

Other readers, however, take issue with the idea that night owls should shift their schedules to fit the 9 to 5 regime. "I think where workplaces can offer more flexible hours they should," someone else told us, adding:

"Of course that's not possible in every industry, and there may be key events that most of the workforce need to be working at the same time for, but increasingly it feels like people could work 12 to 8 rather than 9 to 5 and it really wouldn't affect output in any way—bar making them more productive."

"If anything, it's actually economically illiterate not to offer this as you have a whole host of people working way below their maximum potential, which, morality aside, is simply bad business," the same person asserted.

And night owls do have their advantages, which researchers also acknowledge. One study from 1999 argues that "early to bed, early to rise will likely make you anything but wise," finding that night owls score better on intelligence tests than morning larks.

Furthermore, perhaps unsurprisingly, a more recent study from 2012 found that men who are evening types were able to find more sexual partners, compared with peers who identified as morning people. But perhaps the solution to the "night owl vs morning lark problem" is not black and white, and a measure of change has to come both from society at large, and from individuals, as they "try on" different daily rhythms and find the ones that bring the best results for health.