FRIDAY, June 1 (HealthDay News) -- Sleepless smokers are at greatest risk for poor oral health, according to a Japanese study looking at the risk factors for gum disease.

The researchers tracked 219 factory workers from 1999 to 2003. The workers were evaluated on the following lifestyle factors: exercise, alcohol consumption, smoking, hours of sleep, nutrition, stress, hours worked, and eating breakfast.

Smoking was found to be the leading factor independently associated with the progression of periodontal (gum) disease, according to the report, which is published in the May issue of the Journal of Periodontology. More than 41 percent of the workers with progressive periodontal disease were smokers, the researchers found.

A lack of sleep was the second most important factor. Workers who got seven to eight hours of sleep per night had less periodontal disease progression than those who slept six hours or less per night.

Lead author Dr. Muneo Tanaka said that suggests a "shortage of sleep can impair the body's immune response which may lead to the progression of diseases such as periodontal disease."

High stress levels and daily alcohol consumption also had a significant impact on periodontal disease progression, the study found.

"This study points out to patients that there are lifestyle factors other than brushing and flossing that may affect their oral health. Simple lifestyle changes, such as getting more sleep, may help patients improve or protect their oral health," Preston D. Miller Jr., president of the American Academy of Periodontology, said in a prepared statement.