Are you among those who fight off after-lunch sleepiness with a cup of strong coffee or a high-caffeine soda? You’re certainly not alone.

The days of the 8-hour-night’s sleep are gone for millions of people. But getting 6 or so hours of shut-eye just isn’t enough for many of us. The result can be an annoying feeling of tiredness or, if you’re operating on a patient or flying an airplane, something potentially tragic.

Dr. Sara C. Mednick, an assistant professor at the University of California, San Diego, says a strategic nap is not only restorative but can also seriously help boost workplace productivity.

Mednick, the author of Take a Nap! Change Your Life, says a 20-minute doze resets the system and offers a burst of alertness and increased motor performance.

The problem with caffeine, she says, is that it actually can decrease memory performance. “Coffee can have immediate ‘alerting’ benefits, but not a lot of cognitive benefits.”

By contrast, naps have been shown to offer cognitive improvement without interfering with one’s nighttime sleep. Although people don’t think about a nap in the same category as exercise, both help the body and mind recharge.

Increasingly, employers are finding that permitting employees to catch a few zzzs while they’re on the clock “is good for the business and incredibly lucrative in terms of productivity.”

Offering a nap is also considered an affordable employee benefit.

Mednick says the situation is similar to that of the 1980s when workers started to telecommute. “Employers [at first] thought there was no way that people were going to work from home and be more productive.” But research shows that the combination of lower overhead and letting employees work according to their own schedules resulted in significant savings for many businesses, Mednick adds.

The benefits are even more significant for people in safety-sensitive jobs in which rest can help stave off tragic mistakes.

Mednick points to one study that found doctors working long hours in some cases make 700 percent more errors than those working fewer hours.

According to an August 2010 article on Businessweek.com, in which Mednick is among experts quoted, companies, including Nike, Google, Cisco Systems, and Ben & Jerry’s, are supportive of workplace napping.

Some offer a quiet room with a couch or special napping pods. Others let employees strap on noise-reducing headsets and nod off for a bit while seated at their desks.

The length of a recommended nap is variable. Some people suffer from “sleep inertia,” which makes it hard for them to wake up and feel alert if they’ve slept too long and entered into a period of deep sleep. A nap of about 20 minutes is often just right.

With longer work hours, longer commutes, and less nighttime sleep, the case for napping is clear, says Mednick.

“There’s no way we can do without sleep. Science has not found a way to replace it with a pill. Losing sleep causes an array of problems for health and productivity.”

She says the answer is to optimize schedules by increasing one’s daytime sleep with a nap.

This can be especially vital for people who work changing shifts and rarely get the recommended hours of “nighttime” sleep.

Mednick recommends that shift workers give themselves a productivity jolt by taking a brief nap before they head to work.

Asked about her own habits, Mednick says she’ll typically get a 20-minute nap in during work hours and tries for an hour over the weekend.

She simply closes her office door and sleeps at her desk. If someone knocks, she just doesn’t answer!