The eye opening truth is: Too much screen time is damaging to your eyes. Blue light passes the cornea and lense and penetrates to the retina in the back of your eye. This causes troubling side effects including sleep deprivation, change in melatonin levels and cellular damage.
In an article published in the Jan/Feb issue of The Atlantic, James Hamblin writes; When light enters your eye it hits the retina, which relays signals to the core of the brain the hypothalamus. The size of an almond, the hypothalamus has more importance per volume than any other part of your body. This almond is the interface between the electricity of the nervous system and the hormones of the endocrine system. It takes sensory information and directs the body's responses so the body can stay alive. Among other roles in maintaining bodily homeostasis, appetite, thirst, heart rate, the hypothalamus controls sleep cycles. When your retinas start taking in less light your hypothalamus assumes it's time to sleep. So it wakes up its neighbor the pineal gland and says "hey make some Melatonin and shoot it into the blood, and you become sleepy." All of this is why we are told to minimize screen time before bed. Phones and tablets emit light that's skewed heavily towards the blue end of the visible spectrum and some research suggests that these frequencies are especially influential in human sleep cycles.
Kazuo Tsubota, President of the International Blue Light Society, promotes public awareness of pertinent research on the physical effects of light.