Gazing at a computer screen for too long can make your eyes “tired,” but the underlying physical reasons for that fatigue are murky. Scientists studying people who work at computers for more than 7 hours a day have now found that they have less tear fluid than normal, The Independent reports. In fact, the low fluid levels are comparable to those with dry eye syndrome, a condition where the eye produces an insufficient amount of tears. To help your eyes retain moisture, the researchers suggest placing a humidifier near workspaces and avoiding direct wind blasts from air conditioners. Their study appears online this month in JAMA Ophthalmology.