Sleeping on the job is generally frowned upon, but new research suggests that a nap may boost work performance and productivity.

    A midday snooze doesn't just recharge your body, it also refreshes your brain. Researchers at the University of California Berkeley recently reported that napping can significantly enhance the brain's ability to learn and store new information.

    Most working adults in the U.S. spend roughly 16 to 18 hours awake each day. After a point of maximum alertness, the longer we stay awake, the more lethargic our brains become.

    That's one reason why pulling an all-nighter typically backfires, whether you're a college student cramming for a final exam or an executive rehearsing the most important presentation of your career. Burning the midnight oil can reduce the ability to learn new facts by as much as 40 percent, due to slowed activity in specific brain regions during sleep deprivation.

    Taking a nap can reverse some of the deleterious effects of prolonged wakefulness, rebooting the brain so that it's able to absorb and retain additional information.

    In the University of California study, 39 healthy adults were divided into two groups. Those in one group took a nap, while individuals in the other group remained awake the entire day.

    At noon, subjects in both groups participated in a series of learning exercises designed to challenge the hippocampus, a region of the brain involved in storing fact-based memories. Learning performance was similar in both groups.

    At 2 p.m., the individuals assigned to the napping group retired for a 90-minute snooze, while those in the non-napping group remained awake. At 6 p.m., all of the study participants were subjected to a new bout of learning exercises.

    While performance in the non-napping group deteriorated markedly, subjects in the napping group performed significantly better and demonstrated a greater capacity for learning new information. These findings support earlier research that sleeping helps clear the brain's short-term memory bank and enhances learning ability.

    The researchers also made a novel discovery. Using electroencephalogram testing, which measures electrical activity in the brain, they found that a specific phase of sleep, known as Stage 2 non-REM (Rapid Eye Movement), is the period during which memory capacity is refreshed.

    Humans spend approximately half of their normal, nighttime slumber in Stage 2 sleep. The new finding may help further explain the link between sleep deprivation and poor memory.

    While taking a two-hour siesta in midday may be the norm in Mediterranean countries, working Americans are more likely to engage in shorter snooze sessions, fondly known as power naps or catnaps. The good news is that sleeping just 20 minutes during the day offers many of the same benefits provided by longer naps.

    The results of a study published in the Journal of Sleep Research demonstrated that air traffic controllers scored better on tests of alertness and skill when they took advantage of a planned nap opportunity. Although the workers spent an average of just 18 minutes sleeping, they exhibited measurable improvements in reaction time and overall performance afterward.

    When scientists at Stanford University asked physicians and nurses to take a short nap while working the night shift in an emergency department, job performance improved. After napping, the health professionals exhibited better moods, higher levels of alertness and greater speed in executing job-related tasks.

    A planned nap does more than just boost work performance and productivity, it can also improve your health. In a study of nearly 24,000 Greek adults between the ages of 20 and 86, scientists at Harvard School of Public Health and the University of Athens in Greece found that napping reduced the risk of death due to cardiovascular disease.

    Subjects who napped at least three days a week for an average of 30 minutes were 37 percent less likely to die from heart disease compared to those who never napped. The researchers concluded that napping may improve cardiovascular health by reversing some of the damaging effects of stress.

    Since it's generally not a good idea to nod off unexpectedly, you may want to schedule your naptime in advance. Most daytime workers find it easiest to doze off between 1 p.m. and 4 p.m., when there's a natural dip in energy levels and alertness.

    Although a short siesta can be beneficial, it's no substitute for a good night's sleep. But on days that you need to be extra sharp, taking a brief nap may be the best way to boost your mood, memory and performance.

     
    Rallie McAllister is a board-certified family physician, speaker and the author of several books, including "Healthy Lunchbox: The Working Mom's Guide to Keeping You and Your Kids Trim." Her website is www.rallieonhealth.com.