Any experienced Windows Support person should be able to look at this.
You can find out what triggered the sleep in the event log. Use the Event Viewer app. The log you need to look in is Windows-Logs/System.
It may be VERY BIG. If so it will take many seconds to come up. I never bother to delete it. Go and make a cup of tea.
Open a second copy of the event viewer and if possible put it on another screen.
In first copy, Filter on event ID 42. This will let you find the exact sleep times.
Then look in the other copy at the times that the event 42 occurred. This is the event "The system is entering sleep" but may have various "reasons".
In my case I find that shortly before the 42 event, event 524 occurred, Critical Battery Trigger met.
You just have to look around the time of the 42 event to inspect what has been going on and identify likely items of interest.
To set the filter choose "Filter current log" on the right hand side. Enter your ID's in the middle where indicated. to remove the filter choose "Clear filter". DO NOT CHOOSE "Clear LOG".
It's good idea to make a note of relevant IDs so that you can filter on them again if you have to come back to it. Be careful though you still need to look at the unfiltered log to make sure you are not missing something you have not seen previously.
