woman looking at cell phone with light on face

Friday, August 23, 2019

By Jenny Cartwright MS, RD/LD

Q: I’ve heard about ‘Blue Light’ being harmful, but how can it affect my diet?

A: Blue light is a high wavelength of visible light that penetrates deep into the eye. Too much exposure to blue light can damage light sensitive cells in the retina. Blue light is everywhere, including sunlight, artificial lighting, and digital screens. Eyes are not very good at blocking it. Interestingly, the sky looks blue because of it. It contributes to digital eye strain. During the day the blue light in sunlight boosts our attention, memory, energy levels, reaction times, and overall mood.

 Circadian Rhythm

Blue light affects the circadian rhythm. Exposure of light suppresses production of melatonin. Blue light wakes you up and stimulates you, during the day. It also starts the production of cortisol (stress hormone) and ghrelin (nicknamed the “hunger” hormone). Unbalanced hormone levels can contribute to fatigue. The majority of the exposure of artificial blue light occurs at night. Too much exposure at night from your phone, table, or computer can make it difficult to fall asleep. Depression, obesity, and diabetes have been linked to night time exposure to blue light.

 Weight Gain

A healthy, well balanced diet, exercise, and good sleep habits are vital for positive outcome on long term health status. Weight gain has been linked to blue light exposure at night. With increased stress and hunger hormones and inability to fall asleep one is more likely to consume a “midnight snack”. These are usually caloric dense foods with little to no nutrient values.

 Reducing Exposure

How can you reduce exposure to blue light? Many devices have nighttime setting that minimize blue light exposure automatically in the evening. Computers have “night light” settings. There are blue light blocking glasses that decrease the amount of blue light your eyes are exposed to. You can have this tint added to your prescription lenses or purchase separate non-prescription blue light glasses. Replacing fluorescent lights with incandescent bulbs can also decrease the amount of blue light you’re exposed to. Try limiting screen time in the two to three hours before going to bed. If you there is a TV in your bedroom, do not fall asleep with it on.