Using iPads before bed ‘can lead to a poor night’s sleep’

Neurologists have known for years that staring at screens late in the evening can disrupt sleep – be they television screens, computer screens or mobile phone screens.

However, because cell phones and tablets are by nature portable… more people are taking them into the bedroom.

Users also tend to hold them much closer to their eyes than a computer or television screen.

Researchers at the Lighting Research Center, at the Rensselaer Polytechnic Institute in New York, are warning that looking at tablet displays for more than two hours “leads to a suppression of our natural melatonin levels as the devices emit optical radiation at short wavelengths” – in other words, they emit bluer light.

They say: “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.”

They drew their conclusions after measuring 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 significantly lower after they had done this, than they were after the volunteers had viewed their iPads for the same time, but while wearing orange glass goggles, which cut out the blue light.

They wrote in the journal Applied Ergonomics that tablet makers could “tune the spectral power distribution of self-luminous devices” so that they disrupted the sleep patterns of users less.

It is not just a good night’s sleep that could be jeopardized by too much late night screen time.

Researchers know that persistent disruption to sleep patterns can lead to an increased risk of obesity, and even breast cancer.

However, these studies tend to be comparisons of those with chronic sleep disruption, such as long term shift workers, with those who have normal sleep patterns.

Information appearing on telegraph.co.uk is the copyright of Telegraph Media Group Limited and must not be reproduced in any medium without license. Reprinted here for educational purposes only. May not be reproduced on other websites without permission from the Telegraph. Visit the website at telegraph. co. uk.  (This article was first published at the Telegraph on Sept. 10)