MySQL: How to decrease sleep process's time out?

When I run 'show processlist;', then I get so many sleep processes. I set wait_timeout and interactive_timeout to 60 in my.cnf. But, sleep process is not died when time 60 on processlist. I found that sleep process is died when time is 7900. What happend?? How can I decrease sleep process's time out? If you need other information, I will give information as I possible. **UPDATE** I use root, read_only and deploy account on mysql. And I found root and read_only accounts run correct. Query -> Sleep -(60sec)-> release process. But deploy account, using to connect between rails server and mysql, run wrong. Query -> Sleep -(7900sec)-> release. So, I think that deploy account or Rails is problem. However, I dont have any idea to fix this.