April 26, 2007 :- BOSTON (UPI) -- The ability to make "big picture" inferences from disparate pieces of information is dependent on getting a good night's sleep, says a U.S. study.

"These findings point to an important benefit (of sleep) that we had not previously considered," senior author Matthew Walker of Harvard Medical School said in a statement.

"Sleep not only strengthens a person's individual memories, it appears to actually knit them together and help realize how they are associated with one another -- you go to bed with pieces of the memory puzzle, and awaken with the jigsaw completed."

In the study, college students were shown five pairs of unfamiliar abstract patterns and told that some of the patterns were "correct" while others were "incorrect," but were not told that there was a hidden "hierarchy" linking all five of the pairs.

The findings, published in the Proceedings of the National Academy of Sciences, found the students tested after 30 minutes did the worst; however, students who had some sleep or who had a full night's sleep were able to demonstrate a clear understanding of the interrelationship between the pairs of shapes.

WASHINGTON (UPI) -- A typical night for Deborah Wischow means waking up three hours after an early bedtime and waiting to see if sleep will return.

"You're not asleep, but you're not really awake," said Wischow, a Minneapolis resident who has struggled to maintain sound sleep for the past few years.

Wischow, 49, is one of many American women who are stressed out and sleep-deprived due to poor time management, according to a study released recently by the National Sleep Foundation.

Sixty percent of all women surveyed reported getting a good night's sleep only a couple of times a week, and 46 percent said they had a problem sleeping most nights.

This sleepless existence has gripped women of all ages and walks of life. The women also reported falling asleep at work and relying on caffeinated beverages during the day to stay awake. The survey results contain a 3.1 percent margin of error and were collected from 1003 people between ages 18-64 who where surveyed over the phone.

The 46 percent figure was shocking to Meir Kryger, a leading sleep researcher and doctor who served as chair of the poll's task force.

"To me, that was the most startling number, and not surprisingly. Whenever you hear women talking, it is amazing how often (the conversation) turns to their sleep problems," said Kryger.

Wischow said it seems like no one in her office sleeps. In the corporate world where she works, getting five hours of sleep is normal. "People brag about how much they didn't sleep," Wischow said. "There's not enough time in the day. It's not practical."

To Joyce Walsleben, director of New York University's Sleep Disorder Center, sleep is not a matter of practicality.

"It's absolutely necessary, and if you do it, you begin to understand that. Everybody seems to be happier. We just drag ourselves around with too little sleep and then we get into trouble."

A lack of sleep has put women in a bad cycle of moodiness, said the poll. Being worried or stressed can lead to sleeplessness, which in turn leads to a bad mood, which cycles back to more sleepless nights and possibly depression. One of the big symptoms of insomnia is depression, Kryger said.

"They put sleep on the back burners ... and the next day they are grouchy, irritable, (and) not very productive."

The survey also found working single women get less sleep and have more caffeine than any other category. Most women averaged less than six hours of sleep and 3.1 cups/cans of caffeinated beverages per day.

The most unexpected finding was stay-at-home moms experienced the most sleep problems of the categories, Walsleben told United Press International. Out of all the stay-at-home moms surveyed, 74 percent said they often felt symptoms of insomnia. It could be stay-at-home moms get sloppy with their time management, Walsleben said.

Women who work part time and have children, on the other hand, seemed to have the most balanced lifestyle in the survey. They reported sleeping well, with half of them getting at least eight hours of sleep a night.

"One of the reasons is they are able to schedule things with their family. We may be looking at a group of women that are better at balancing things," said Kryger.

Though 60 percent of women in their 50s said they got at least eight hours of sleep a night, 41 percent reported using sleep aids. And 44 percent of those without any children in the home, or "empty nesters," reported getting good sleep most nights.

But why are women getting less sleep than men? Walsleben said females have a different psychological makeup, and they tend to care for -- and worry about -- the people around them, and then take those issues to bed with them. The traditional role of women also has something to do with sleep deprivation.

Sleep deprivation has become a regular habit for many. Wischow, a divorced mother of teenagers, has gotten used to little sleep and says she doesn't really take it seriously anymore.

Taking the steps to getting enough quality sleep involves purpose and discipline. For those with sleep disorders, the National Sleep Foundation recommends keeping a standard bedtime, relaxing during the hour before bed and including exercise in the day. However, exercise should be at least three hours before bedtime.

And for people like Wischow who find sleep elusive, Walsleben suggests simply adding 15 minutes onto a normal night of sleep every night until the person gradually reaches a healthy period of slumber.

"There's nothing in our lives that we can't cut out," she said.