Secret Behind You Should not Use Smartphones After 9 at Night

Using a smartphone after 9 pm may leave workers disengaged and kill their productivity the next day, a new study has warned.

Night-time smartphone work drains employee effectiveness in the morning, according to the study by Christopher Barnes from the University of Washington Foster School of Business.

"Smartphones are enormously valuable for helping people fit work activity into times and places outside of the office," said Barnes and colleagues who summarised their paper in a Harvard Business Review blog post.

"However, our new research indicates the greater connectivity comes at a cost: using a smartphone to cram more work into a given evening results in less work done the next day. Smartphones are bad for sleep, and sleep is very important to effectiveness as an employee," they said.

Barnes said that smartphones keep us mentally engaged with work late into the evening, making it harder to detach, relax, and sleep deeply to recharge our batteries.

He added that managers need to find creative ways to balance the downside of smartphone use with the significant upside of this powerful work tool.

One possible solution cited is adopting predictable time off each day, a set time to power down and psychologically disengage from work. Another is establishing new norms of when employees are expected to respond to e-mails.

"As smartphones become more embedded in our daily lives, we should continue to seek solutions that will enable us to stay in touch with smartphones and still get the sleep we need to be effective the next day," researchers said.