Why are some people early birds and others are night owls?

As I write this, my part-time workday is just beginning, yet my husband is tucked into bed, dreaming sweet dreams about tennis matches and Corvettes and other stuff he loves ... at 9:29 p.m. He is your quintessential early bird, and although I don't quite qualify as a night owl, I definitely prefer to turn in a little later in the evening than he does, and certainly rise later than his standard 5:30 a.m.

It turns out that my hubby is a relative rarity, as only about one in ten people qualify as true early birds, or larks (hitting the hay around 9 p.m.), while two in ten classify as owls, burning the midnight-or-later oil on a consistent basis. The rest of us (myself included) fall somewhere in the middle, often referred to as hummingbirds, and are comfortable switch-hitting as needed for social or work-related purposes, though we may have owlish or larkish tendencies [sources: Smolensky and Lamberg, Breus]. It's pretty easy to spot true morning people because they consistently start their days early, even on the weekends, whereas night people who are forced to function on a normal weekday schedule relish a good sleep-in.

Although I've always been of the opinion that this behavior is learned, science is doing its darndest to prove me wrong. In fact, research seems to point squarely at genetics as the culprit for whether someone wakes up bright-eyed and bushy-tailed or not. "Recent discoveries suggest that there are 'clock genes' that run human circadian rhythms," explains Michael Breus, Ph.D, DABSM, author of Secrets to Sleep Success.

Specifically, changes to a gene known as PER1 can affect early bird/night owl status, as it's a component of a larger group of genes known to impact circadian rhythms. Apparently, even minor variations to PER1 can affect your body's natural rise-and-shine time, and it appears that our bodies are primed pretty much from birth to have specific preferences [source: Borreli]. This genetic wild card probably explains why some of us have longer circadian rhythms, resulting in night owl status, as opposed to morning people with shorter internal clocks [source: Oakley].

Next, let's take a look at some of the bizarre ways these sleep preferences affect our personalities, success and even — gulp — time of death.

Early Birds vs. Night Owls

They're not exactly rival gangs, but most people who fall into one of these two categories feel pretty strongly about their preferred bedtimes. Although there are definitely exceptions to every rule, research has shown that early birds and night owls tend to exhibit specific personality traits and other tendencies. First, the good news: evening people are generally pegged as more outgoing, creative, intelligent and even having a better sense of humor than early risers. Unfortunately, their unique circadian rhythms have also been credited with higher incidence of ADHD, insomnia, depression, anxiety and addiction issues, to name a few.

By contrast, morning people are more optimistic, and therefore better able to fend off these problems, possibly due to their own genetic makeup. Larks also are more stable, conscientious and feel healthier and happier overall than night owls, perhaps because they experience more normal sleep patterns. Early birds are naturally synced up with the majority of business and educational schedules, helping them earn better grades and be generally more successful in the workplace, often resulting in higher wages [sources: Blaszczak-Boxe, Oakley, Randler]. Of course, there are exceptions to every rule, so it's totally possible to be a content night owl at the top of your corporate game.

Hormonal changes can affect our preferred sleep schedule throughout our lives, with adolescents generally moving into evening-preferred territory around age 13. Most people under 30 continue to enjoy a somewhat later schedule, but by age 50 or so the majority shift into early-riser status [source: Randler]. I'd like to refute that, but the older I get the less my stupid internal clock lets me laze about on weekend mornings. At this rate, I'll be popping out of bed at 5 a.m. by the time I retire.

Making the Switch From Owl to Lark

Even for us moderately inclined hummingbird types, it can be difficult to live in an early bird world, particularly if you lack a taste for caffeine-laden coffee. Many couples find it challenging to live with someone on the opposite spectrum, since most of us like to share more than a couple of waking hours with our significant others. Whether you're hoping to beat that nauseatingly chipper guy to the promotion or avoid a "ships passing in the night" sort of relationship, there are ways to adjust your internal clock accordingly.

"Morning light exposure for a night owl will help reset the circadian clock," says Dr. Breus, adding that this measure will ideally halt the production of melatonin. Done over a period of a couple of weeks, such efforts will help shift a night owl somewhere closer to the middle. "I think it would be tough to get a true night owl to become an early bird," he says. Simply opening your curtains probably won't do the trick, though. Experts suggest physically taking yourself outside in the morning if a shift to an earlier schedule is what you desire. Exposure to the direct morning light will help your circadian rhythms to adjust accordingly, just as spending time outside in the evening will have the opposite effect [source: Randler].

Most experts agree that modest change is probably the best-case scenario for true night-timers, since it appears that 50 percent of such tendencies are purely genetic [source: Randler]. If you've given living on the opposite schedule a fair shot and just can't seem to make it work, it might behoove you to consider career aspirations that are more in tune with your natural preferences. Job opportunities with flexible or overnight schedules include a range of healthcare positions (doctors, nurses and techs), writers, artists and bartenders. By contrast, larks are ideally suited for careers in education, manufacturing, banking and general business, to name a few.

Fortunately, more companies are jumping on the flexible scheduling/work-from-home bandwagon, which is helping people of all schedule persuasions cope with time of day preferences. Now, if only we could get them to adopt universal napping policies, we'd be sitting — and sleeping — pretty.

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Author's Note: Why are some people early birds and others are night owls?

Here's hoping science will yield a cute name for what I really am: someone who likes to go to bed early and sleep in late. Followed by an early afternoon nap.