It might be time to give your smartphone a curfew. Two new studies reveal that using your phone past 9 PM can leave you sapped of energy the next day.
One plainly obvious reason, according to the daily surveys of 82 upper-level managers and 161 employees, was that when people use their phones at night for business reasons, they tend to stay up later. The physiological reason is that phone's blue light hinders restful sleep -- even more, surprisingly, than watching television or using a laptop or tablet before bed.
If you're feeling tired and less productive than usual, your late-night smartphone usage could be to blame.