Using light emitting e-readers or tablets for bedtime can be damaging for your sleep and possibly your health. Researchers of Harvard Medical School in the United States discovered people using an e-reader needed more time to fall asleep, had less deep sleep and were more tired the next morning, the BBC reports.
The culprit is blue light that's also emitted by smartphones, laptops and LED lights. According to the scientists the body clock can be disrupted by the devices. The body of people exposed to blue light produces less of the sleep hormone melatonin which makes it harder to sleep.
The research was performed by having 12 people sleep in a sleep laboratorium. The first five days they read a regular book before getting to sleep, the next five days they read a book on an iPad. Blood tests showed the body produced less melatonin when reading on the tablet. The subjects that read on the Ipad also had a harder time falling asleep and they were more tired the next day.
While the research was performed with an Ipad, the researchers claim their conclusions are also valid for other light emitting electronic devices because they also emit light with similar wavelengths.
The results were published last Monday in the magazine Proceedings of the National Academy of Sciences.
On computers with Windows, Linux and Mac and iOS the software F.lux is available to counter the effects of blue light. The app adapts to the time of day, with warm light at night and light like like sunlight during the day which should make it easier to fall asleep after using light emitting devices.
