Let me first start by saying that waking up early has made a huge difference in my life. I used to be the complete opposite - late sleeper and late riser. These days, I wake up at 5:30am everyday.
“Our study shows that a two-hour exposure to light from self-luminous electronic displays can suppress melatonin by about 22 per cent,” Figueiro says in a statement. “Stimulating the human circadian system to this level may affect sleep in those using the devices prior to bedtime.” ... "Figueiro recommends dimming your backlit devices at night to minimise melatonin suppression"