Every company wants engaged employees. Numerous studies show that such employees consistently outperform their less motivated peers, creating better products, more revenue, and more profit.

However, there's a dark side to having employees who consistently go the extra mile: burnout. As Tony Schwartz recently pointed out in The New York Times:

"Last week, Fortune magazine released its list of the top 100 companies to work for, compiled by the Great Place to Work Institute. I'm familiar with many of the companies on the list. I'm not aware of a single one that isn't struggling with the issue of employees who feel exhausted and pushed to their limits."

In other words, people who love their jobs end up working so hard that they start to hate their jobs, at which point their personal productivity plummets.  

I've personally seen this happen to numerous people, especially in startups and large high-tech firms; heck, I've ridden that one-hump roller coaster a few times myself.

Some companies deal with this phenomenon simply by accepting it. They push employees until they burn out and then discard and replace them.

Hiring and training new people, though, can be expensive. What if there was a way to keep employees motivated without burning them out?

It turns out that this silver bullet may actually exist, and what's more, it's relatively cheap to implement.

According to research to be presented this week at the annual meeting of the Academy of Management, the main source of employee burnout is the expectation that emails will be answered after hours.  The study notes that:

"An 'always on' culture with high expectations to monitor and respond to emails during non-work time may prevent employees from ever fully disengaging from work, leading to chronic stress and emotional exhaustion."

What's fascinating about this finding is that the burnout results not from the volume of work or the extra hours of work but from the "mere expectation that workers will respond to email in their off-hours."

For example, suppose an employee is putting in 10-hour days seven days a week. While that's obviously a heavy workload, it needn't result in burnout as long as that employee is allowed to completely disconnect for the 14 hours he or she isn't actually working.

Conversely, employees working an average of eight hours a day, five days a week will be prone to burnout if they know that a boss, customer, or client might email at any time of day or night with the expectation that the employee will respond.

To keep your motivated employees from burning out, all you need to do is make it perfectly clear that work emails need only be answered during work hours.

Yes, that will involve a little discipline on the part of management and employee alike, but the potential benefits are enormous. 

Indeed, over the past few years, I've been running into an increasing number of people who simple do not answer emails sent during off-hours. Despite (because of?) not being plugged in, they seem to get more accomplished than the folks who are available 24/7.  And they don't seem to burn out.

And that's seriously good news for everyone.