Take Two #119: Sleep cycles, more than just a habit

By Kyra-lin Hom

I'm sure you've heard the term 'night owl' before. What about its counterparts 'morning lark' and 'hummingbird?' All three are common references for human sleep patterns: night owl and morning lark are self explanatory extremes with the flexible hummingbird landing right in between. But did you know that these aren't just casual social categories? They are in fact lay terms for different chronotypes. New research is proving that these aren't just habits. They're in our genetics.

It's true. Among other as of yet indistinct genetic factors, the Beth Israel Deaconess Medical Center has located one specific gene variant that can, on its own, extend an individual's natural circadian rhythm (internal clock) by a full hour. In an unrelated study, the University of Chicago found that night owls have on average more testosterone and cortisol (hormones associated with stress, energy, arousability and cognitive function) than non-night owls. Germany's Aachen University's brain scans of people of different chronotypes further revealed that night owls have less white matter (fatty tissue that aids communication between the neurons) in their brains than morning larks.

That all comes together to create two very distinct types of people. True night owls, with their longer circadian rhythms and high hormone levels, may take longer to get started but have greater stamina to keep going once they get there. They are statistically more productive individuals with special talents for risk-taking and analytical tasks, making them often test to a higher IQ. The downside is these good qualities also come with a penchant for drugs, alcohol, depression and addiction in general. Plus the constant stress of sleep deprivation caused by forcing a 'normal' schedule (think school and work) is what erodes that white brain matter. Researchers call this chronic “social jet lag,” which can permanently reduce the number and production of brain cells in a night owl's head (or anyone's for that matter) according to the University of Pennsylvania.

Morning larks on the other hand tend to be overall more balanced, organized and happier individuals. Sure, they (counterintuitively) don't get as much done and they might not solve that bonus extra credit test question, but they are loving life.

Before you diagnose yourself keep reading. Psychologist Frederick Brown of Pennsylvania State University says that only about 17% of the population are true night owls. Morning larks are even rarer at just 1%. These are people who's chronotypes will remain stable for their entire lives. A true night owl or morning lark at age 15 will still be one at age 80. Everyone else falls somewhere in the middle.

These intermediates (hummingbirds) go through chronotype cycles instead: early risers as children, night owls as teenagers and then a steady progression back into morning lark territory as they age. Intermediaries can adjust their sleep schedules with effort. True night owls and morning larks can't. (Though this shouldn't reduce the significance of those chronotype cycles.)

Now I know I just said no diagnosing yourself, but I'll go out on a limb here (albeit a sturdy one) and call myself a night owl. My perfect world would have 28-hour days. I just don't get tired when other people do, and natural light therapy does nothing for me. My whole life it hasn't mattered how early I get up (even regularly for work or school), midnight is still 'early' for me. My mornings just get blearier and blearier until I pass out for a full 12 hours come Saturday – oh, my poor dying neurons.

Thankfully, all of tthis research is bringing legitimacy to the social jet lag problem. The more studies reveal, the more scientists are pushing for an adjustment to society's inflexible rhythm. A few schools are even starting to offer the option of delayed start times. Were I in high school now, that would be my holy grail. For now though, we'll just have to wait for the rest of the world to catch up.

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