Light-emitting devices such as smart phones, tablets, LCD TVs, and e-books can disrupt sleep. Scientific American in August 2015 states, "light from our devices is “short-wavelength-enriched,” meaning it has a higher concentration of blue light than natural light—and blue light affects levels of the sleep-inducing hormone melatonin more than any other wavelength".
Such stressors affect systemic hormonal and neurological functions which in turn shifts the body's natural clock (circadian rhythm). This resetting of our internal clock then affects other physiological functions of other organs. Particularly the blue wavelength which if found in high levels in these electronic devices mentioned.
So how do you mitigate the damage and reduce or stop the shifting of our cycles? There are a number of proactive things you can do... for those that cannot turn off the devices long before bedtime. These involve two approaches. One is just to dim the device to reduce the impact of the light. The second is to use a program to filter out the short wavelength light in the evening. Some programs even will do this shift automatically as it notes the time of day in your timezone such as F. lux app. You can buy tinted lenses to reduce the high energy blue light and they also have reflective coating which helps the glare from overhead lights (Gunnar Haus glasses). Another approach at the other end of the night is to use a color adjustable hue lightbulb to fill the bedroom with blue rich white light in the morning. Then at night you use a deep red light bulb... just like the military use in sleeping quarters at night (Philips Hue Go).
If you think we have issues... astronaut orbiting have a 90 minutes sun rise and set!! NASA works on these wavelength principals as well. Protect your sleep ... think about the light color and your sleep will be sounder.