Hi @spatulaclub,
The sleeping processes mean memcached is doing its job. With memcached answering many of the queries that MySQL did before, those processes aren’t active & will sleep.
The only reason I can think of to clean out the sleeping processes is if your server is low on memory. Then again, if it’s low on RAM, you would be better off to configure MySQL to have fewer processes all the time.
Keeping the processes alive will help in the rare case that your server gets a large number of requests that memcached doesn’t have data for. I think a major search spider hit on your site might do that, b/c it would request every known page instead of the frontpage + new content pattern that humans tend to follow. By having those MySQL processes alive your server would have slightly lower latency answering those requests. Because it would already have more RAM allocated to MySQL & not need to start additional processes.