If you’re like me, you may find yourself using your smartphone to answer work emails right before going to bed. But I may try to break that habit, as new research has found that using a smartphone at night can make you less productive the next day at work!

Two recent studies found that people who use their smartphones after 9:00 PM have more trouble sleeping and feel “more tired and less engaged” at work the following day. The researchers cite two major reasons that explain this finding. First, the psychological reason: when you mentally engage with work problems before bedtime, your brain can have trouble winding down and relaxing to get to sleep. Second, the physiological reason: the “blue light” emitted by the smartphone’s screen has been found to disrupt melatonin production. In fact, blue light is the most disruptive to melatonin of all colors of light.

So unless your work issue demands immediate attention, you may want to try turning off the phone after dinner and winding down without it. Who knows what great things you’ll be able to accomplish at work the next day?