Sleeping on the job was once considered taboo, but today, more companies are encouraging employees to take a mid-shift snooze. And it’s a wise practice: 29 percent of workers report falling asleep or becoming very sleepy at work, and a lack of sleep costs the United States $63 billion each year in lost productivity.

But a twenty-minute nap can boost alertness and improve performance—both important when you’re on the job.

“We look out for our employees’ quality of life, and providing space and time for naps is just another way for us to take care of the people who work there,” says a representative at the Burlington, Vermont-based Ben & Jerry’s. The company supplies a room with a bed and pillows that employees can use as needed. “If people need to catch a little snooze during the day to do the best possible job they can do, we’re behind it,” says the representative.

Zappos, the online shoe retailer known for fully subsidized employee health insurance, has had a nap room at their Las Vegas, Nevada, headquarters since they launched. “It was born from our focus on employee happiness and wellness,” says a representative. “We know how much sleep impacts well-being.” The rooms are available 24/7, and are especially frequented by those on staff who work overnight shifts.

Athletic giant Nike offers staffers quiet rooms, where they can nap or even meditate during the day. And at Google’s Mountain View, California, home base, employees take advantage of campus-wide nap pods — futuristic-looking lounge chairs that play soothing sounds so workers can catch a quick snooze when they need one.

Another important bonus of napping: improved employee performance. In the 1990s, NASA recognized sleep’s crucial role for astronauts and experimented with short naps during their workdays. Performance skyrocketed; today, the “NASA nap” is a common practice among pilots making international flights for airlines such as Continental and British Airways.