If you're having trouble sleeping at night, the answer may be as close as your iPad.
Researchers at the Lighting Research Centre, at the Rensselaer Polytechnic Institute in New York, claim that the blueish light from an iPad screen can mimic daylight,, convincing the brain that it is still daytime.
The researchers' study, published in Applied Ergonomics, said that blue light stops the production of a brain chemical called melatonin, which helps us fall sleep.
However, light that is more orange or red in tone does not suppress melatonin production, because human brains recognize the colors as the sunset and "think" the day is ending, reports Telegraph.co.uk.
The researchers said: “Although turning off devices at night is the ultimate solution, it is recommended that if these devices are used at night displays are dimmed as much as possible and that the time spent on them before bed should be limited.”
The researchers measured melatonin levels in 13 volunteers, after they had spent time viewing iPads at full brightness at a distance of 10 inches, for two hours.
Melatonin levels were much lower than they were after the volunteers had viewed their iPads while wearing orange glasses, which eliminated the blue light.