Simplified Science #3: Cell Phones & TVs Make You Fat

Tech abuse: are you guilty of it? When we get home from our often times device-driven work environments, we wind down by watching tv, surfing the net on tablets and laptops or playing on our phones. We even fall asleep with our TVs on and think nothing of it!

That's where light pollution comes in. It's well established that the artificial blue spectrum of light emitted from common screens is harmful to our health. This is because blue-light exposure supresses melatonin, which prevents us from getting high quality sleep. However, new research is beginning to show blue-light isn't the only type of light that is causing health issues.

Our bodies expect to be exposed to about 12 hours of light followed by 12 hours of complete darkness. Unfortunately due the complications of modern life, we're almost never in complete darkness. This constant exposure to light (artificial or natural) disrupts our biological clocks and wreaks havoc on our health. In essence, our bodies don't know when it's day or night time anymore.

In installment #3 of the Simplified Science series, we look at research published in the Proceedings of the National Academy of Sciences of the United States of America which examines the effect of prolonged light exposure on body fat.

What Journal?:

Proceedings of the National Academy of Sciences of the United States of America


Mice were exposed to either 12, 16, or 24 hours of light for 5 weeks in order to assess the biological effects of prolonged light exposure

Additional Info:

Note: This particular study was conducted on mice, not humans.


  • Compared with the mice exposed to 12 hour of light, the mice exposed to 24 hours of light had a significant increase of fat mass.

  • Light exposure influenced body fat mass in a dose dependent manner, meaning that as light exposure time increased, so did body fat mass.

  • White adipose tissue (the sloppy, metabolically inactive fat) was significantly increased in mice exposed to 24 hours of light compared to 12 hours.

  • Prolonged light exposure decreased Brown Adipose Tissue (the healthy, fat-burning type of fat) activity.

  • Note: This is important because Brown Adipose Tissue has a role in blood sugar regulation and metabolism. You want more brown adipose tissue and less white adipose tissue.

  • Prolonged light exposure decreases activity of AMPK (a cellular enzyme with powerful anti-aging properties).

  • The chart below shows that BAT fat activity decreased as light exposure time increased.

The takeaway:

Prolonged light exposure is linked to increased body fat storage. Our body's "good fat" decreases as light exposure time increases. Additionally, our body's "bad fat" increases as light exposure time increases. This study shows that constantly being exposed to light wreaks havoc on our health. It's vital that we allow ourselves to be in complete darkness for at least 8 hours per day. This can realistically be acheived during sleep. Investing in blackout curtains and keeping electronics out of the bedroom are two good ways to eliminate light exposure while you sleep.

Leave a comment and let us know what you think!


Kooijman, S., van den Berg, R., Ramkisoensing, A., Boon, M. R., Kuipers, E. N., Loef, M., … Rensen, P. C. N. (2015). Prolonged daily light exposure increases body fat mass through attenuation of brown adipose tissue activity. Proceedings of the National Academy of Sciences of the United States of America, 112(21), 6748–6753.

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