Uh the My Cloud DOES have a “sleep” function. Its right there on the My Cloud Dashboard under Settings > General > Energy Saver > Drive Sleep. Now does that sleep function work 100%? That’s a different story and one can search these subforums (magnifying glass icon upper right) to find the numerous threads that discuss the sleep issues and various methods to try and get the My Cloud to consistently sleep for long periods of time. There is an unofficial sleep.awk script one can run on v4.x firmware version My Cloud’s to see how often the My Cloud is actually sleeping.
https://community.wd.com/t/new-sleep-awk/153431
The My Cloud will generally, when the sleep option is enabled (set to ON), go to sleep after 10 minutes of inactivity. Unofficially one may be able to use SSH to change the sleep time from 10 minutes to some other value. Use the forum search feature to find one or two prior discussions on changing the sleep time out value.
If you want WD to add a new feature then feel free to post that idea or feature request in the Cloud Ideas sub forum where often such requests are made:
https://community.wd.com/c/personal-cloud-storage/cloud-ideas
When it comes to USB hard drives attached to the My Cloud not going into sleep or low power mode, there has been discussion on that front as well. Best suggestion there is to use a USB hard drive that puts itself into low power or sleep mode independent of the computer or device it is connected too.
When the My Cloud is in sleep mode the front LED, which is blue when the My Cloud is operating normally, should slowly pulse blue.
