Once again, I’m up late writing (it’s almost midnight), but that is a natural thing for me to do, given that I don’t actually become wide-awake until about 5 PM. That’s the way it’s been for me for as long as I can remember. Back in college, my grades started going up once I gave up on those 7:40 AM classes, and tilted my day toward the late morning through mid-afternoon. Quite often, I will get to work at about 10, working until seven or eight at night. This allows me to harness more of my peak time to do the challenging job I do (I am a consumer attorney).  Several times a month, I find myself at the office writing a legal brief at one in the morning, working quite effectively.

It’s not that I don’t like to sleep.  I love to sleep.  It’s just that I love to sleep in.   That’s when it feels natural to me.    I know that it’s not merely a matter of biology.  I stay up late because I want to get one more thing done, and then one more thing.   I hate to give up the day, even when it turns into the next day.  for me, there’s no better time for concentrating than the night.  For whatever combination of nature and nurture, the night is my favorite time.  I am an owl.

Those other kinds of people, those “larks,” often look at owls with suspicion, however. Even when owls spend as much time at work as larks, the larks assume that we owls are goofing off in the morning while they are working hard. What about those evening hours while we owls are still hard at work while the larks are long gone? Larks think that this is our own damned fault and the owls should be getting up earlier. I do think this is part of the Larkian thought process. This perceived tension has often provoked me to think about why it is that my schedule is tilted toward the afternoon and evening. Do I choose for it to be this way or am I biologically geared to be an owl? And why is it that so many owls (me included) end up marrying larks?

In “Of Owls, Larks and Alarm Clocks,” Melissa Lee Phillips reports on out-of-sync body clocks in the March 12, 2009 issue of Nature (available online only to subscribers). I learned quite a few things from this article. For instance, I learned that half of the population in industrialized societies have circadian rhythms that are “out of phase with the daily schedule they keep.” I learned that people living out of phase are said to have “social jet lag.” I learned that many people become “owl-ish” when they spend lots of time indoors. I learned that working out-of-sync is serious business.

If larks and owls are forced to follow normal schedules, they run into all kinds of problems with disabling insomnia and sleepiness. . . . in 2007 . . . [World Health Organization] concluded that “shift-work that involves circadian disruption is probably carcinogenic to humans . . . equally strong conclusions have been drawn from evidence that links circadian-rhythm problems to psychiatric disorders, metabolic syndrome and a range of other illnesses.

Phillips reports on a Denmark study suggesting that women forced to work on the night shift for at least six months R1 .5 times more likely to develop breast cancer than those who work the day shift. The scientists suspect that this timeshift might cause the body’s cells to start dividing at the wrong time and “run amok.” She reports that numerous people with major depression have sleep abnormalities.

Phillips also reports that scientists are working hard to figure out what kinds of schedules are healthiest for the various biological clocks are we exhibit. She indicates that our tendency to be a lark (or an owl or something in between) is referred to as our “chronotype.”  Our chronotype might shift over our lifetime, but it is thought to be largely determined by our genes. According to Phillips, adolescents and young children tend to be more owl-like than children or older adults.

The conclusion to the article is that it is not a problem per se to be a lark and owl. The problem is forcing yourself to live a schedule that goes against your own biological clock.