Interesting but sobering new research was published recently looking into how exposing our bodies to artificial light may increase the risk of obesity.

The study showed that in 100,000 women of 16 years and older this exposure resulted in obesity even when factors such as alcohol intake, physical activity and the number of hours spent asleep were taken into consideration.

It seems that the disruption of our natural circadian rhythmn – how our bodies respond to the natural cycle of darkness and light – can affect our metabolism which may result in weight gain and obesity risk for some individuals.

Dr. James Gangwisch of Columbia University who has been studying the effects of sleep disruption on metabolic health says “If metabolic changes resulting from nighttime light exposure are contributing to the obesity epidemic, it may be beneficial to take measures to limit this exposure.”

Sources of artificial light

We live in a world where we are increasingly exposed to unnatural light especially at night: the screens on TVs, hand held devices used for gaming or reading, laptops and computers, mobile phones etc.  Those who live in cities or more urban areas have the added exposure of all night street lighting.

Research from Harvard Medical School has shown that energy efficient LEDs in light bulbs, computer screens, phones, tablets etc are harmful to the wake sleep cycle.

TVs, laptops, hand held devices are rich in blue light.  This affects light sensors in the retina which are tuned to night-day cycle.  Artificial light inhibits sleep-promoting neurons (brain cells) and the hormone melatonin which aid sleep, and activate neurons that boost alertness.

Dr Karrie Fitzpatrick from Northwestern University in Illinois, states: “having computer screens held close to your face exposes you to more light than watching a TV that is on the opposite side of room”.  This proximity tells the brain to stay awake and resets circadian rhythm resulting in disturbed sleep.

So how do we minimise our risk of articificial light exposure?

  • Put down your phone, laptop, tablet, or any device that is emitting a ‘blue light’, at least 1 hour before bedtime.
  • If you have a clock in your room with a digital display replace it or cover up the screen
  • If street lighting affects you, hang up black out curtains
  • remove TVs from bedrooms!
  • Research shows that it is important to expose our bodies to natural light so get out and about!  Even getting out of the office during your lunch hour will help.
References:
  1. McFadden E, Jones ME, Schoemaker MJ, Ashworth A, Swerdlow AJ. The relationship between obesity and exposure to light at night: cross-sectional analyses of over  100,000 women in the breakthrough generations study. Am J Epidemiol. 2014 Aug 1;180(3):245-50.
  2. Gangwisch JE. Invited commentary: nighttime light exposure as a risk factor for obesity through disruption of circadian and circannual rhythms. Am J Epidemiol. 2014 Aug 1;180(3):251-3.