Contrary to popular belief, more Americans commit suicide in summer than in winter, and the day of the week when individuals are more likely to take their own lives has shifted from Monday to Wednesday, sociology professor Augustine Kposowa and graduate student Stephanie D’Auria found.

In a paper published online by the journal Social Psychiatry and Psychiatric Epidemiology, Kposowa and D’Auria examined data for all deaths by suicide in the United States over a five-year period, from 2000 through 2004.

They analyzed data from the U.S. Multiple Cause of Death Files and found that the highest percentage of suicides (24.6 percent) occurred on Wednesdays and the lowest percentage was reported on Thursdays (11.1 percent). That finding contradicts decades of earlier research, which suggested that suicides peak on Mondays.

A second major finding of the study is that more people are likely to take their lives in summer (26 percent) than in winter (23.8 percent). Springtime is a close second at 25.8 percent.

Kposowa said the findings challenge any view of seasonal affective disorder — mood changes related to a change in seasons, sometimes referred to as winter blues — having an effect on when suicides are more likely to occur.

Previous studies that showed suicides peaking in winter (December, January and February) were done before e-mail, cell phones and Blackberries telephones permeated American culture, making it easier to stay connected with friends and family during the Christmas and New Year’s holidays.

“We need to refine assumptions we have made about mental states, mental disorders and suicide, especially when we link them to social support and loneliness,” Kposowa said.

It’s possible, Kposowa said, that the higher percentage of suicides occurring in summer and spring is related to the propensity of Americans to judge themselves by “relative deprivation — keeping up with the Joneses.”

“In summer people are traveling and displaying more of their luxuries, such as automobiles, attractive homes and expensive vacations,” he said.

“We are constantly comparing what we have and what we think we should have against what others have. Life tends to begin in spring and passions come to life, so to speak. We begin to make these comparisons. Some people decide they are unable to have a better life or believe that life is not worth living.”

Knowledge of day or season when suicides are more likely to occur could help clinicians and therapists in advising patients and potential victims, said Kposowa and D’Auria.