There is NO official solution to the sleep issue on the single bay My Cloud’s. There are NUMEROUS threads on the sleep issue with various suggestions that while they work for one person may not work for the next. There are several causes for why the single bay My Cloud’s will not sleep for more than 10 or 15 minutes. Do a forum search for “sleep” to find the many threads. Here are but a few with some suggestions:
Note: Some of these possible workarounds may only apply to the first generation single bay My Clouds (v4.x firmware) and not the newer second generation single bay My Clouds (v2.x firmware).
http://community.wd.com/t/wd-my-cloud-randomly-wakes-up-the-drive-when-drive-sleep-is-enabled/152748
http://community.wd.com/t/mycloud-does-not-go-to-sleep-standby-perhaps-the-solution/158591
http://community.wd.com/t/this-resolved-my-cloud-sleep-mode-issue/157059
