If you use the forum search feature (magnifying glass icon upper right) and search for “sleep” you will find many past discussions on the infamous lack of sleep issue with these single bay/single drive My Cloud units. Some are able, using SSH to disable various services, to get their My Cloud to sleep for long periods of time. Others, my self included, haven’t had much luck no matter what’s been tried to get one’s My Cloud to sleep for even six hours at a time.
One of the first steps is to use SSH to stop the “wdmcserverd” and “wdphotobmergerd” services. That seems to help some with the sleep issue. Here are a sampling of past discussions on the sleep issue, there are a great many more threads than these.
Because there are two generations of the single bay My Cloud and each used different firmware (first gen v4.x firmware and second gen v2.x firmware) the methods and services to stop to try and deal with the sleep issue may be different.
One issue I’ve experienced that prevents lack of sleep is the fact that any time I boot or bring out of sleep/hibernation mode a Windows PC, it triggers the My Cloud to wake. The issue is apparently related to Samba (SMB).