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.