Studies prove that blue light might cause insomnia and disrupt biological 
clock 

Study done by researchers at Harvard University indicates that using smart phones, tablets, or laptops prior to going to sleep 
throws the body's biological clock, the circadian rhythm, out of rhythm. As a result not only does sleep quality suffer but research
also shows that it may contribute to the causation of cancer, diabetes, heart disease, and obesity. Exposure to light suppresses
the secretion of melatonin, a hormone that influences circadian rhythms. There is experimental evidence the lower melatonin
levels might explain the association with cancer.

Professor Richard Funk, a Famous German ophthalmologist, had his report Blue light can Seriously Threaten Retinal Neurons
published by the European Journal of Neuroscience in August 2011. The report pointed out that continuous exposure of blue light,
especially the light of LED lamps, smart phones, and computer screens, which contain large amounts of high-energy shortwave
blue light with irregular frequencies will cause vision problems.

How Blocking Blue Light at Night Can Transform Your Sleep
Authority Nutrition

Medical studies prove that blue light to increased risk for cancer

Study after study has linked working the night shift and exposure to light at night to several types of cancer (breast, prostate),
diabetes, heart disease, and obesity. It's not exactly clear why nighttime light exposure seems to be so bad for us. But we do know
that exposure to light suppresses the secretion of melatonin, a hormone that influences circadian rhythms, and there's some
experimental evidence (it's very preliminary) that lower melatonin levels might explain the association with cancer.

Even dim light can interfere with a person's circadian rhythm and melatonin secretion. A mere eight lux - a level of brightness
exceeded by most table lamps and about twice that of a night light—has an effect, notes Stephen Lockley, a Harvard sleep 
researcher. Light at night is part of the reason so many people don't get enough sleep, says Lockley, and researchers have linked
short sleep to increased risk for depression, as well as diabetes and cardiovascular problems.

Blue light has a dark side
May, 2012   Harvard Health Publications