"Massive changes over the past half-century have reshaped the workplace, with major implications for sleep. For many workers, psychological stress has replaced physical hazards," said Sarah Burgard, a sociologist at the university. "Physical strain at work tends to create physical fatigue and leads to restorative sleep, but psychological strain has the opposite effect, making it more difficult for people to sleep."
So before you blame your employees' sub-par performance on sleep deprivation, you might want to consider whether it's the office environment rather than their own after-hours activities that's keeping them up at night. If there are workplace problems afoot -- especially interpersonal conflicts -- resolving them might help get your people get more shut-eye. And than can improve their productivity and efficiency.
On the plus side, the study found no evidence that long hours or working nights or weekends led to poor sleep quality. So feel free to pile on the overtime (in a nice way, of course).