Why do the months of April and May have the highest suicide rates?

I always feel slightly down in April and May for no apparent reason, and I recently read a newspaper article that commented that these are the months with the highest suicide rates. Does anyone know a scientific reason for this? One website (a href="http://www.myselfhelp.com/News/Newsletter/0504.html#2)" rel="nofollow"http://www.myselfhelp.com/News/Newslette…/a speculated on a few potential ideas, but are have there been any official studies that offer more than speculation?