Are you a night owl or early bird? A new blood test claims to know.

Getting a good night's sleep just took on a whole new meaning.

  • A new study introduces a new method for determining your personal circadian rhythm.
  • This could have profound effects on combating cognitive disorders and helping patients understand when to take medicine.
  • The blood test measures a person's biological clock to within 1.5 hours.

Though the light bulb isn't exactly a hot new piece of technology, at the time of initial dissemination it created a social revolution whose effects — positive and negative — are still felt today. No matter how much awe we feel flying over the bright jigsaw of a metropolis, the unintended damage electric lighting waged on our sleep patterns is in part to blame for a number of modern ailments, including obesity, Type 2 diabetes, hypertension, cardiovascular disease, and cancer.

Until a few centuries ago all life was governed by the rhythm of the sun. Earlier technologies, such as controlled fire and candles, require constant upkeep while causing nowhere near the same damage as the blue lights on our phones. What we call advancement comes at a cost — for example, the physical and emotional health of teenagers.

As journalist and high school science teacher Henry Nicholls recently wrote in the NY Times, three out of four high school students do not get eight hours of sleep per night. This is extremely damaging during a time of great neuronal development. Nicholls argues that an 8:30 a.m. start time is counterproductive and dangerous:

It is unthinkable that a school should operate with asbestos in the ceilings, with no central heating in winter or with rats in the kitchen. Starting school before 8:30 a.m. should be equally unacceptable.

Such an early start time is mostly the result of parental convenience: in a two-parent household where both adults work, dropping the kids off at school considers their schedule. Unfortunately, such a timeline usurps basic biology. Teenagers should be sleeping more than eight hours, yet the combination of an early first period and late-night chats and gaming on smartphones has created an environment not conducive to learning.

Photo: Yuris Alhumaydy / Unsplash

The human circadian rhythm approximates with the rising and setting of the sun, though that's not the final word in this story. Before electric lights we slept in two shifts — still within the timeframe of the rotation of the planet, however. As Daniel Pink writes in When, his book on timing, there is individual variation in this rhythm: 14 percent of humans are what he terms "larks" and 21 percent "night owls," while the majority are "third birds," meaning their midpoint of sleep is between 3–4 am.

How do you know what feathered vertebrate you are? It turns out your blood can tell you. A new test called TimeSignature, announced in a study published in the Proceedings of the National Academy of Sciences, requires only two blood draws to inform you what your genes say about your circadian rhythms.

This follows previous, expensive tests requiring numerous blood draws at specific times of the day. TimeSignature measures forty different gene expression markers that signal when you should be sleeping. Though variation might exist dependent upon scheduling — I remember gruelingly working overnight shifts in the emergency room back in college — your genetic make-up doesn't lie.

Now we can pinpoint the hours we should be unconscious with previously unavailable precision. According to Northwestern University Feinberg School of Medicine assistant professor (and lead author of the study), Rosemary Braun,

This is a much more precise and sophisticated measurement than identifying whether you are a morning lark or a night owl. We can assess a person's biological clock to within 1.5 hours.

Poor sleep patterns are also implicated in two devastating health issues beyond those mentioned above. First, not honoring your nightly requirement factors into mental health problems and neurological disorders. Second, when you take a dose of medicine matters. TimeSignature might aid in informing doctors when their patients should be swallowing pills. As coauthor Phyllis Zee says of the study's findings,

This is really an integral part of personalized medicine. So many drugs have optimal times for dosing. Knowing what time it is in your body is critical to getting the most effective benefits. The best time for you to take the blood pressure drug or the chemotherapy or radiation may be different from somebody else.

Coauthor Ravi Allada notes that almost every tissue and organ system in our body depends on our personal circadian rhythm. The fact that certain mental health disorders, obesity, and even cancer can be avoided by knowing when you should be sleeping is a groundbreaking step forward in modern medicine, even if it is basic common sense: a good night's rest is folk wisdom.

That said, little seems common when we've shut nature out of our lives in so direct a fashion. From electricity to blue lights to virtual reality headsets, one light still matters most. The ancients would honor that star by naming their gods after it; today, fearing skin cancer, we shelter ourselves at every turn. Yet there it remains, dictating our every bodily process even as we remain ignorant of the fact. With this new test, such ignorance might just be abandoned.

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Stay in touch with Derek on Twitter and Facebook.

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