我可以依赖使用语句关闭MySQL连接吗?

I have an ASP.NET website that uses mysql as it's database. I notice there are a lot of connections "sleeping" when I show a full process list. Today we had some errors "The timeout period elapsed prior to obtaining a connection from the pool.". If the processes are "sleeping" then are they still open from the code? All MySQL connections in the code are in using statements. Can I rely on the using statement to properly close connections?I have an ASP.NET website that uses mysql as it