Using cellphones, tablets before bedtime affects sleep.

If you feel headache while sleeping or it difficult to fall asleep at night, the reason could be over usage of gadgets at bedtime. Researchers in the US have found using an electronic gadget for just two hours before the bedtime can cause sleep problems, Daily Mail reported Wednesday.
 

The new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute believes the displays cause melatonin suppression. Melatonin is the chemical that controls our body clock. Researchers believe that the teenagers are particularly susceptible to the problem. "Our study shows that a two-hour exposure to light from self-luminous electronic displays can suppress melatonin by about 22 percent," said Mariana Figueiro, associate professor at Rensselaer and director of the LRC's Light and Health Programme.

Figueiro says that stimulating the human circadian system to this level may affect sleep in those using the devices prior to bedtime.  Source-- tech2