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October 5, 2012 at 9:50 AMComments: 3 Faves: 0

We're All Part of a (Circadian) Rhythm Nation

By Kyle McCarthy from SLN More Blogs by This Author

Raise your hand if you listen to music when you doze off to sleep. Do you work the night shift? Is there an annoying street lamp outside your bedroom window that floods your sleeping quarters with incandescence? How often do you wake up and trudge to the kitchen for a midnight snack?

About a Day

If you routinely experience or engage in any of these examples, it could mean bad news for your health. Evidence suggests that a shift in contemporary living habits has significantly altered our lifestyles, thus causing us to lose the beat of our circadian rhythm (biological processes dictated by temporal rhythms). Circadian rhythm – from the Latin for “about a day” affects metabolism, physiology, and behavior, and it directly contributes to our overall health and wellness.

Western society is currently living by different rules than human beings have followed for the last 50,000 years. We live hectic, fast-paced lives with vast, sweeping shifts from intense pressure, to extreme relaxation. Our traditional sleeping patterns are off, our traditional eating patterns are off, and our traditional working patterns are off.


The problem is that, as light is the battery behind our body’s clockworks, we have become synchronized with the sun over thousands of years. Now, within a speck of known time, we have eradicated this once exclusive relationship by relying on artificial light from a variety of sources. In fact, the presence of artificial light during what have historically been sleeping hours could explain the nearly universal and simultaneous rise of dozens of health conditions across a wide spectrum since the middle of the 19th Century.

As members of the most technologically gluttonous society on the planet, Americans have developed into a nocturnal culture. We stay up late watching Kimmel, playing Halo III on Xbox, or writing term papers about The Big Sleep that are due the following day. For most of us, following a set bedtime is a relic of a distant and forgotten past (the ‘80s). The more common habit is to glue ourselves to some form of entertainment or task until we simply can’t stay awake any longer, and then basically just pass out.

Of Mice and Men

Obviously, inconsistent sleep patterns like these have substantial effects for our body’s circadian rhythm. When our circadian rhythm gets out of sync, the release of hormones is affected, and we struggle to maintain our homeostasis. In fact, exposure to artificial light during or directly before regular sleeping hours increases your chances of developing health conditions such as depression, obesity, and even cancer. As Dr. Cathy Wyse says, “The human clock struggles to remain tuned to our highly irregular lifestyles, and I believe this causes metabolic and other health problems.”


One of these health problems is obesity. Dr. Wyse conducted a study with mice in which their circadian rhythms were purposefully thrown off kilter. This resulted in severe changes to the mice’s metabolism and the way they breakdown fat and sugar. Therefore, the mice began to gain significant amounts of weight, despite ingesting the same amount of food on a daily basis as the mice in the control group. Obesity has long been believed to be the product of an unhealthy diet coupled with a lack of exercise, but this study suggests that Americans’ unnatural circadian rhythm could be contributing our weight problems.

Health Issues

Obesity isn’t the only health issue that appears to be related to our body’s internal clock. Depression is also closely related to a disruption in circadian rhythm. Often times, when people aren’t eating healthily, socializing regularly, or working regular hours, they also don’t get enough quality sleep, so much so that these poor sleeping habits develop into full-blown insomnia. According to Rubin Naiman, Ph.D., there’s a definite linkage between this insomnia and depression. In a column he wrote for “Psychology Today,” he posits,

Tired and Depressed

"The depression-insomnia complex is usually preceded by a lengthy period of anxious and obstinate acceleration through life, sans a psychological spoiler. Why are we surprised that after years of bounding mindlessly over nature's speed bumps -- of failing to brake, slow and rest at night -- we find our circadian rhythms to be so out of alignment?"

Not only can circadian rhythm affect obesity rates and depression, but it can even contribute to cancer. Recent studies conducted at the University of Haifa in Israel suggest that melatonin production, which normally occurs during the down time of the circadian rhythm (i.e. during sleep), is suppressed when sleeping people are exposed to artificial light. When melatonin isn’t produced, cancerous tumors grow more often and more rapidly. Prof. Abraham Haim, author of the study, attributes this phenomenon to the advent of artificial light: “Exposure to LAN (light at night) disrupts our biological clock and affects the cyclical rhythm that has developed over hundreds of millions of evolutionary years that were devoid of LAN.”

Like most self-imposed health risks, righting our lifestyle is entirely up to us. Balancing our sleep schedules with our daily periods of activity can be a difficult task, but the studies above imply that it’s imperative if we hope to maintain a healthy lifestyle. I think the question we should ask ourselves is: If we could avoid severe health risks by turning off the television before we fall asleep and keeping a consistent nightly routine, wouldn’t it be a worthwhile endeavor?


Boyce, P & Barriball, E. (2010). Circadian rhythms and depression. Australian Family Physician, 39(5), 307-310.

Cohen, Tamara. ( 2012, August 30). Disrupting your body clock can make you fat: Keeping regular sleep and meal times helps stay slim. The Daily Mail. Retrieved from

Feldman, R. (2012, September 2). Light at night and cancer. University of Haifa Press Releases Retrieved from

Navara, K.J. & Nelson, R.J. (2007). The dark side of light at night: Physiological, epidemiological, and ecological consequences. Journal of Pineal Research, 43(3), 215-224.

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  • Great article Kyle. Halo 3 all-nighters....old school memories.

  • Great blog. I can see how my own life has changed with the addition of children, night lights, and disrupted sleep.

  • It's funny how study after study seems to be showing us that as a species we're literally too smart for our own good. We've found ways to beat nature - but our bodies haven't been able to evolve fast enough. All the ease and convenience we enjoy comes at a definite price. By almost every measure, be it in the energy we exert, the food we take in, or our exposure to plants, animals or the sun, ect, when we deviate from what is natural, we suffer.

    Great article, Kyle. Fascinating stuff. :)

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