You're no Marie Curie.

That was the painful accusation lobbed at me by a reader in response to an essay in which I presented some scientific arguments (real scientists', not my own!) for cognitive differences between women and men.

It hurt. Sure, I'm a writer, an English major, and the only college-level science class I ever took was "Human Biology," a bonehead course designed to help arts majors fill out their requirements for graduation. But I love to read about neuroscience and evolutionary biology and to think and write about what I have read. And, like Madame Curie, who exposed herself to deadly radiation in the name of scientific discovery, I am willing to make certain sacrifices to further my own understanding of human biology.

This is why, for two weeks in the middle of an extremely busy life, I allowed myself to become a guinea pig testing the scientific theories of the Nap Lady.

Take a nap, change your life
When I first heard her on NPR's "Talk of the Nation," research scientist Sara Mednick, affectionately known as the Nap Lady, was explaining that there is "an intelligent way to sleep" and that napping is a skill like any other--one you have to practice to perfect. Dr. Mednick--her PhD in Psychology is from Harvard University--had recently completed a three-year fellowship at the Salk Institute for Biological Studies and published a book based on her findings: Take a Nap! Change Your Life.

Taking a nap sounded like a really good idea at the time, and I was also feeling a definite need to change my life. I logged on to Mednick's website, where there first thing I did was take a test to determine my level of daytime sleepiness. According to the Epworth Sleepiness Scale--which asked me to rate how likely I felt I was to doze off under a variety of conditions, from sitting and reading to sitting in a car stopped in traffic--I was a desperate case. With a score of 17 (people with narcolepsy score about 17.5), I was suffering from "severe sleepiness. People in this range should speak to their physicians about testing for a sleep disorder, while also being sure to take regular naps."

Since the people I know who have submitted themselves to sleep disorder testing have come home with machines they must hook themselves up to every night like recharging cyborgs, I decided to begin with just the regular naps part of the prescription. Fortunately, Mednick's website also features the Take a Nap Nap Wheel, designed to show you the optimal time of day to begin changing your life. Because I had bullied myself out of bed at 7 that morning, the Nap Wheel suggested that I take my nap around 2 p.m., at the point in the day where my REM (Rapid Eye Movement) and slow-wave sleep cycles were predicted to intersect.

At the appointed hour, I closed my laptop, lay down on the couch, and promptly fell asleep.

Why does sleep feel so good?
Sleep, like food, is something that our bodies need, and our bodies reward us with pleasurable feelings when we do things that promote their survival. But in contrast to our fairly complete understanding of nutritional needs, we're still in the dark about why we and our fellow animals need to sleep. Looked at from an evolutionary point of view, the fact that a sleeping animal can't do any of the usual things required to insure the survival of a species--hunt food, procreate, defend oneself from predators--suggests that slumber must offer some significant adaptive advantages to outweigh the risks of this behavior.

Recent studies indicate that at least one of the crucial functions of sleep is to aid memory and learning. Robert Stickgold, a cognitive scientist at Harvard and one of the country's leading sleep researchers, theorizes that while we're snoozing our brains evaluate information we've recently learned and make decisions about what to do with it. Memories and skills acquired during our waking hours are consolidated and stabilized; patterns and rules are extracted from all the data we've accumulated over the course of the day.

Stickgold and other researchers have designed experiments showing evidence of links between sleep and cognitive performance. In one study, participants were tested to see how quickly they could distinguish the orientation of diagonal lines against a background of horizontal ones. When the same subjects were retested later in the day, their skills had not improved significantly, but when they came back for testing after a night's sleep, their performance was significantly better. Subjects who were not allowed to sleep the night before the retest did not improve.

Sleep's effect on workplace productivity
Other studies have found connections between sleep and competent decision-making, creative thinking, insightfulness, and short-term memory. Since these are all skills in high demand by organizations fighting to compete in a global economy, it's not surprising to learn that there is also a connection between sleep and workplace productivity.

Researchers at the University of Pennsylvania
found that participants whose sleep was restricted to six hours per night (instead of the recommended eight) over the course of two weeks displayed significant deficiencies in cognitive functioning that included a reduced ability to pay attention, to think quickly without making mistakes, and to multi-task.

When you consider that, according to the National Sleep Foundation (NSF), 64 percent of all Americans get fewer than the recommended eight hours of sleep each day, the Sleep Institute's estimation that poor sleeping habits are costing U.S. businesses some $18 billion a year in lost productivity seems entirely plausible. Results of a recent NSF survey suggest that the problem is only getting worse: 40 percent of respondents reported that they were working more hours than they were five years ago, while 38 percent said they were spending less time sleeping than they were five years ago.

Sleep experts are pretty sure they know where those extra work hours are coming from. They say that few American workers are getting the amount of sleep their brains are programmed to require. "People think that sleep is negotiable--that their only choices are to stay up later or to get up earlier," says Dr. Mark Mahowald, a neurologist in Minneapolis. "They wear sleep deprivation as a badge of honor." Worse, most people don't recognize the impact insufficient sleep is having on their performance. "You're phenomenally stupid when you're sleep deprived, and you're too stupid to realize it," Robert Stickgold told a reporter for The Wall Street Journal, adding, "We are the only known organism that sleep deprives itself."

Wake up and nap
The good news is that some of the negative effects of sleeping less at night can be ameliorated by sleeping a little bit during the day and, as Sara Mednick says, "There's always time for a nap."

Along with Stickgold and Ken Nakayama, Mednick carried out an experiment which showed that a 60-to-90-minute nap had learning benefits similar to those provided by night-time sleep. Even a short 10-20 minute snooze can help increase alertness and reaction time, not to mention improve your mood.

Of course some Latin and Mediterranean cultures have practiced the siesta or resposo for centuries; modern science is only beginning to measure the benefits. The Archives of Internal Medicine recently reported on a six-year study of nearly 25,000 Greek adults that showed that those who napped for a half-hour at least three times a week had a 37 percent lower risk of death from heart attacks than those who didn't take a midday siesta.

While the United States is still a relatively nap-averse society (when's the last time you heard a colleague brag about how much sleep he gets?), U.S. businesses such as Nike and Deloitte & Touch are starting to provide employees with "relaxation rooms" and "napnasiums" where they can catch forty winks at will. Workman Publishing, which brought out Mednick's book earlier this year, is walking the talk in its New York office, where graphic designers, editors, and publicists can be found napping on designated yoga mats.

As for me, after two weeks of napping every afternoon for at least 20 minutes, I am happy to report that I have reduced my daytime sleepiness score to 7, which "indicates normal sleep function." Although I can't prove I've been more productive as a result, I certainly feel more productive and alert and agreeable in the afternoon than I did in my pre-napsarian days. Plus, the whole undertaking is extremely pleasurable. Napping hasn't exactly changed my life, yet, but I'm determined to keep trying.

Debra Wierenga is a full-time writer and mother who gets more sleep than you do.