Gadgets like Smartphones, tablets and e-readers should be in automatic "bedtime mode" so it will stop disturbing people's sleep, according to a leading doctor.

 Prof Paul Gringras, a doctor from Evelina Childrens's Hospital in London argued that the setting should be able to filter out the blue light that interrupts the body clock and keeps people conscious shortly into the evening.
 
But regarding to him every new released model was "bluer and brighter", so he wants to catch the attention of the manufacturers to be more responsible with their products of Smartphone, tablets and e-readers.
 
A hormone called melatonin is produced by the body in order to help people to sleep. This process occurs when it gets darker and darker in the evening. But the system can be distracted by definite of wavelengths of light, those at the blue-green end of the spectrum.
 
A study analyzing the light emitted by devices was published in Frontiers in Public Health and Prof Gringras was a part of it. The study also concludes that an obvious trend for new launched devices to be larger, brighter, have higher height of contrast can release more blue light.

The Prof Gringras a professor of children's sleep medicine said to BBC News website: "That is great for use in the day, but awful for use at night.
"There is converging data to say if you are in front of one of these devices at night-time it could prevent you falling asleep by an extra hour."

He also said that there are some sleep-aware apps had previously been designed to lessen blue-green light emissions. Software such as f.lux already has a bedtime mode that could repeatedly sort out the blue.

He said it is considered necessary for the manufacturers to be more responsible and the main "key is to automate it".

"It's not good enough to say do less and accept this is the world we live in, they're fun devices but we do need some protection on what they do at night-time.," Prof Gringras added.