MONDAY, Oct. 10 (HealthDay News) -- There may be some truth to the expression "cleanliness is next to godliness" after all, finds a new review of previously published studies.

University of Michigan researchers found that showering and hand-washing help people rid themselves of bad feelings, such as guilt, sadness or doubt.

"Cleansing is about the removal of residues," said researcher Spike W.S. Lee. "By even just thinking about washing themselves, people can rid themselves of a sense of immorality, lucky or unlucky feelings, or doubt about a decision."

The review was published in the latest issue of Current Directions in Psychological Science.

In examining previous studies, researchers found that people exposed to a messy room or bad odor judged others more harshly for moral wrongs than when they were sitting in a clean room.

In a separate study, researchers showed that people felt less guilty while thinking of something immoral they had done if they used an antiseptic hand wipe. As a result, they were also less likely to volunteer for a good cause in order to ease their guilty conscience.

The review authors also said that people who perceive themselves as "clean" feel morally superior to others and may judge them more harshly.

Physical cleanliness may also help people shed feelings of bad luck. The researchers said gamblers who washed with soap believed doing so had also "washed away" their bad luck -- so they made even bigger bets.

"Cleansing removes the residual influence of earlier experience," said Lee in a journal news release. That applies to both happy memories and bad ones, the authors said.

They added that sanitizing the particular body part associated with a wrongdoing may have a more significant mental cleansing effect. For instance, another study revealed that liars prefer mouthwash to other types of cleansers.

More information

The U.S. Centers for Disease Control and Prevention has practical tips on hygiene.