Just want to give a shout-out to the excellent resource for all your Mac challenges: MacinTouch. It's a daily compilation of issues and suggested fixes provided by Mac users.
This is the link to the El Capitan main page, but you can go back to the root and climb out on another...
I have been using the option of preventing certain applications from napping. The check box was in the get info box. In El Capitan it appears to have been removed. This is causing me a real pain as I try and send newsletters through an email service.