Warning: Using your smartphone in the dark may lead to temporary blindness

  • Study says using a smartphone in the dark may trigger temporary blindness
  • Having one eye against a pillow while using a smartphone makes the eyes unable to adjust to the dark which causes the vision loss 
  • It is ultimately harmless but can be an unsettling experience

The seemingly harmless habit of checking an email or chatting on social networks while lying in bed just before going to sleep at night can actually harm your vision and even trigger temporary blindness, a new study warns.

A study published in the  New England Journal of Medicine described the cases of two women, aged 22 and 40, who customarily checked their smartphones while in bed and ended up suffering severe loss of vision in one eye for up to 15 minutes at a time over several months.

Doctors often mistake these symptoms for a transient ischemic attack  or a mini-stroke – a warning sign that a major stroke is on the way.  They were subjected to a variety of medical exams, MRI scans and heart tests. Yet doctors couldn’t find anything wrong with them to explain the problem, until they consulted with an eye doctor.

“I simply asked them, ‘What exactly were you doing when this happened?'” said Gordon Plant of Moorfield’s Eye Hospital in London.

Plant examined the women and found that their late-night smartphone habits contributed to this temporary blindness. He explained that the blindness was brought on by the fact they were looking at their smartphone with one eye while the other rested on their side in bed, blocking the light from the screen, as per an article published by Independent.

“So you have one eye adapted to the light because it’s looking at the phone and the other eye is adapted to the dark,” he said. “and it’s taking many minutes to catch up to the other eye that’s adapted to the dark.”

One of the women was relieved the short-term blindness did not signal a more serious problem like an imminent stroke. While the second woman was more skeptical and kept a rigorous months long diary tracking her fleeting vision loss before she finally believed Plant’s hypothesis but is still unable to break the habit.

This transient smartphone blindness is ultimately harmless but it’s unsettling to individuals who experience it. The best way to avoid this is to make sure that when you’re using your phone in the dark, keep both eyes on the smartphone screen.