Boffins at the Department of Recreation and Leisure Studies at East Carolina University have revealed that 'casual' video games can reduce stress and have other mood-lifting effects.

The news follows a six-month, randomised, controlled study sponsored by casual gaming firm PopCap Games.

The hypotheses were tested by measuring subjects' heart-rate variability, electroencephalography and mood states before and after playing Bejeweled 2, Peggle and Bookworm Adventures.

In all cases, the changes in stress levels and mood were measured in comparison to a control group that experienced a web-based activity similar in physical and mental nature to the game-playing groups.

Mood was measured in six different categories (Psychological Tension, Anger, Depression, Vigour, Fatigue and Confusion) which combine to provide a 'total mood disturbance'.

The scientists explained that a decrease in 'total mood disturbance' represents a positive change in mood.

Playing Peggle had the greatest effect, improving mood by 573 per cent across all study subjects compared to the control group.

Bejeweled 2 (435 per cent) and Bookworm Adventures (303 per cent) also had significant positive effects on subjects' overall mood.

Interestingly, male subjects who played Bejeweled 2 showed a 10 per cent greater increase in total mood than female subjects, while females who played Peggle experienced a 40 per cent greater improvement in mood than males.

"It is not surprising that Peggle had the greatest effect on overall mood, given the game's over-the-top celebration of players' success each time they complete a level," said Carmen Russoniello, director of the study.

"The other games also provide positive feedback to players, but not to the same extent or in the same 'exhilarating' fashion."

The results of this study are "impressive and intriguing", according to Russoniello, given the extent of the effects of the games on subjects' stress levels and overall mood.

"I believe there is a wide range of therapeutic applications of casual games in mood-related disorders such as depression and in stress-related disorders including diabetes and cardiovascular disease," she said.

East Carolina University's Psychophysiology Lab is planning to start clinical trials later this year to determine the efficacy of these games and their prescriptive parameters.