Now that workers are able to access email and websites at any time from almost any location via smartphones, they can be responsive to professional demands in ways unimaginable only a few decades ago.
Customer-centric organisations can remain attentive to clients’ needs around the clock. Time-critical events can be addressed quickly. People can leave their offices without fear of being disconnected from their work. Indeed, many would consider smartphones to be among the most important tools ever invented, when it comes to increasing the productivity of knowledge work.
However, our new research indicates that 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. The reason for this is that smartphones are bad for sleep, and sleep is very important to effectiveness as an employee.
That a well-rested employee is a better employee is well established by research. Insufficient sleep has been linked to more unethical behaviour at work, cyberloafing, work injuries and less organisational citizenship behaviour.
Unfortunately, smartphones are almost perfectly designed to disrupt sleep. Because they keep us mentally engaged with work late into the evening, they make it harder for us to psychologically detach ourselves from the most pressing cares of the day so that we can relax and fall asleep.
More generally, they encourage poor sleep hygiene, a set of behaviours that make it harder to both fall asleep and stay asleep. Perhaps the most difficult aspect of smartphones to avoid is that they expose us to light, including blue light. Even small amounts of blue light inhibit the sleep-promoting chemical melatonin.
EVEN WORSE THAN TV
As researchers, specifically, we hypothesised that a greater number of minutes spent using smartphones after 9pm would more negatively affect sleep; that this in turn would leave people feeling tired in the morning; and that, as a result, they would be less engaged at work the next day.
To test that hypothesis, we conducted a pair of studies.
In our first study, we had 82 mid- to high-level managers complete multiple surveys per day for two weeks. We compared each individual’s daily data only with that person’s own data on other days. Consistent with our hypotheses, we found late-night smartphone usage cut into sleep and made people tired in the morning and that, as a result, they were less engaged at work the next day.
In the second, we had 161 employees from a broad variety of occupations (both managers and non-managers) complete the same set of surveys, with the addition of late-night usage of television, laptop computers and tablets.
The harmful effects of smartphones on sleep and work engagement held even after accounting for these other electronic devices. Indeed, out of all those devices, smartphones were associated with the most powerful effects.
Our study adds to a pile of scientific evidence that managers must begin to acknowledge. There are downsides to having employees use smartphones — direct ones for the employees and less direct but still troubling ones for workplaces. Smart managers will look for creative ways to minimise the problems without giving up the mutual benefits of smartphones.
AGREE ON TIME OFF
One solution suggested by Harvard Professor Leslie Perlow, based on her research on high-end consultants, is to have predictable time off. And the best way to start is by agreeing that evenings and normal sleeping hours are the most important times for people to be predictably “off”.
This will allow employees to psychologically disengage from work and minimise exposure to the blue light produced by electronic display screens.
Another potential solution calls for creating new norms as to when employees are expected to respond to work email and when they are not.
Leaders should be sensitive to how their personal behaviours shape norms; employees will not feel pressure to check their mail late in the evening if their bosses are not using that time to send messages. A handy tool is to set a delivery delay on email so that it arrives the next morning, for managers who are travelling or working odd hours. © 2014 Harvard Business School Publishing Corp
ABOUT THE AUTHORS:
Christopher M Barnes is an Assistant Professor of management at the University of Washington’s Foster School of Business. Klodiana Lanaj is an Assistant Professor of management at the University of Florida’s Warrington College of Business Administration. Russell Johnson is an Assistant Professor of management at Michigan State University’s Eli Broad College of Business.