“Most employees use their smartphones in bed at night, which is problematic because the “blue light” that smartphones emit interferes with the production of melatonin, a chemical that facilitates falling and staying asleep,” said Lanaj, the lead author of the project. “Using smartphones for work at night also interferes with employees’ ability to detach and recover from work. Ruminating about impending deadlines or work responsibilities consumes cognitive resources leaving employees more depleted in the morning and less engaged at work the following day.”