Blame Thomas Edison for your abdominal fat  (how to use light exposure to get healthier)

Here are some intriguing research findings:

  • People with lighter bedrooms gain more weight over time (read full study here).  
  • People who work the night shift have more metabolic disease (read more here).  
  • People living in cities with more nighttime light pollution have higher risk of overweight (read more here).  
  • People who exercise in the morning—in front of a bright light—lose more fat than people who do the same routine minus the bright light (read full study here).

Do you find this as fascinating as I do?! 

At first, I couldn’t believe these findings, but they start to make sense once you learn about the metabolic implications of the body’s circadian rhythms.  It turns out our circadian rhythms are like an internal clock regulating the timing of numerous bodily processes…kind of like an orchestra conductor cuing each different instrument to come in at the right time during a symphony.

Our natural rhythms are optimized for us to do certain things during daytime—like eat, digest, and be active—and to do different things at night—like sleep, heal, and recover.  Until the invention of electricity, our external cues of light and darkness always reinforced our natural circadian rhythms.  We were in light during the day; it was dark all night.  There weren’t too many ways to get around this.  This was a good thing because our circadian rhythms kept our bodily processes in sync.

But now, according to experts, thanks to modern inventions like electricity, lightbulbs, computers and TV screens, our bodies and brains are getting bright light exposure long after sundown.  And this sends signals to our cells that it’s daytime….even if it’s midnight.  This can cause our inner circadian rhythms to get disturbed.

Why care?

We apparently pay a high price for confusing or disturbing these rhythms.  It’s like the orchestra conductor cuing the wrong instruments at the wrong times, creating a cacophony instead of a symphony.  That’s the metaphor used by the authors of an article called “Metabolic implications of circadian disruption”.  It has this ominous message:

“The process of metabolism is also under circadian regulation. Loss of synchronization between the internal clock and environmental cues [e.g. light vs dark] results in disruption of the circadian rhythms that seriously impacts metabolic homeostasis leading to changed eating behavior, altered glucose and lipid metabolism, and weight gain. This in turn augments the risk of having various cardio-metabolic disorders such as obesity, diabetes, metabolic syndrome, and cardiovascular disease.”

Another article titled “Missing The Dark:  Health Effects of Light Pollution” states:

“The 24-hour day/night cycle, known as the circadian clock, affects physiologic processes in almost all organisms. These processes include brain wave patterns, hormone production, cell regulation, and other biologic activities. Disruption of the circadian clock is linked to several medical disorders in humans, including depression, insomnia, cardiovascular disease, and cancer, says Paolo Sassone-Corsi, chairman of the Pharmacology Department at the University of California, Irvine, who has done extensive research on the circadian clock. “Studies show that the circadian cycle controls from ten to fifteen percent of our genes,” he explains. “So the disruption of the circadian cycle can cause a lot of health problems.” 

This means we can stay healthier and leaner by reinforcing our circadian rhythms with properly timed lightness or darkness.  So the first trick is to reduce bright light exposure after dark, perhaps by:

Wearing blue light blocking glasses if you spend time in front of a screen after sundown,

Changing screen settings to automatically switch to night mode after sunset,

Favoring non-screen activities at night, and

Getting a sleep mask or blackout shades for bedroom windows.

The second tip is to get a few minutes of bright sunlight in the morning, when it reinforces our circadian rhythms.  Between about 8-11am has been found to be ideal.  

The payoff might be larger than you think.  Having a light/dark schedule that mirrors nature is thought to help improve blood sugar control, appetite, cravings, energy, metabolism, cancer risk, weight management, mood and more.  All that from some well-timed light!