The Other Circadian Rhythms

We’ve talked before about how circadian rhythm pertains not just to when it is ideal for us to sleep or be awake, but also at what times it is best to eat, exercise, and so forth:

The Circadian Rhythm: Far More Than Most People Know

Most people just know about the light consideration, per for example:

• How light can shift your mood and mental health, and
• How light tells you when to sleep, focus and poo

When your body parts clock on and off at the wrong time…

Now, new research has brought attention to how these things and more are governed by different physiological clocks within our bodies—and what this means for our health. In other words, if you are doing the various things at different times than you “should”, you will be training the different parts of your body (each with their independent clocks) to be on a different schedule, and so the different parts of your body will out of temporal sync with each other.

To put this in jet-lag terms: if your brain is in New York, while your heart is in Istanbul (not Constantinople) and your gut is in Tokyo, then this arrangement is not good for the health.

As for how it is not good for your health (i.e. the consequences) there’s still research to be done on some of the longer-term implications, but in the short term, one of the biggest effects is on our mood—most notably, increasing depression scores significantly.

And even more importantly, this is in the real world. That is to say, until quite recently, most data we had from studies on the circadian rhythm was from sleep clinic laboratories, which is great for RCTs but will always have as a limitation that someone sleeping in a lab is going to have some differences than someone sleeping in their own bed at home.

As the researchers said:

❝A critical step to addressing this is the noninvasive collection of physiological time-series data outside laboratory settings in large populations. Digital tools offer promise in this endeavor. Here, using wearable data, we first quantify the degrees of circadian disruption, both between different internal rhythms and between each internal rhythm and the sleep-wake cycle. Our analysis, based on over 50,000 days of data from over 800 first-year training physicians, reveals bidirectional links between digital markers of circadian disruption and mood both before and after they began shift work, while accounting for confounders such as demographic and geographic variables. We further validate this by finding clinically relevant changes in the 9-item Patient Health Questionnaire score.❞

Read in full: The real-world association between digital markers of circadian disruption and mental health risks

That questionnaire by the way sounds like an arbitrary thing they just made up, but the PHQ-9 (as it is known to its friends) is in fact the current intentional gold standard for measuring depression; we share it at the top of our article about depression, here:

The Mental Health First-Aid That You’ll Hopefully Never Need ← the test takes 2 minutes and you get immediate results

Want to know more?

For more about getting one’s entire self back into temporal sync (hey, wasn’t that the plot of a Star Trek episode?), sleep specialist Dr. Michael Breus wrote this excellent book that we reviewed a little while back:

The Power of When: Discover Your Chronotype—And Learn the Best Time to Eat Lunch, Ask for a Raise, Have Sex, Write a Novel, Take Your Meds, and More – by Dr. Michael Breus

Enjoy!