Burnout is legendary in our business. It's almost impossible to talk to someone who's been around for awhile without hearing tales of at least one project that turned into a death march. Sometimes this is the result of poor management, capricious deadlines and the factory worker mentality that continues to grow in our industry. Other times people knowingly shoot themselves in the foot with the greatest of enthusiasm. We're passionate about what we do, so long stretches of overtime are often a self inflicted wound. Either way, it spells trouble for your company.
Patton observed that tired soldiers are pessimistic solders. As we all know, that state of mind leads to lack of effort and poor decisions. If this happens in an environment with life and death consequences, it can certainly happen to you.
If you're not careful all that hard work your people are putting in will run your company straight into the ground. It doesn't matter how critical your deadlines are, you need to make sure you find a way for your people to take a break on a regular basis. Not only will their productivity increase, you'll save yourself a wealth of pessimism and negativity that are guaranteed with any death march worth its boots.
It's not enough to not work. In addition to time away from their jobs, you also need to find diversions, something else that their body, mind and spirit can embrace. That's the only way people can truly let go of their work. This is why high level executives will go climb a mountain or take on other such dangerous hobbies. Because inattentiveness could kill them, they're forced to be completely absorbed in the task at hand. By definition, that leaves no room for work in their minds, and thus they truly get a break.
Whatever it takes, be sure you put as much effort into recharging your people as you do working them. While it may seem like wasted time in the short run, the benefit to their morale and the increased enthusiasm with which they return will more than balance it out.