Hi. I had a Windows PC with this problem several years ago. If I recall correctly, the issue was related to the power settings in my case, although, there are other circumstances that can affect sleep mode. Please take a look at this information:
https://www.technipages.com/windows-10-wont-sleep
I assume we are talking Windows 10?
Let’s see if that link is helpful. If not, I can help you dig into the problem further.
“I assume we are talking Windows 10?”
3 week old PC so yes Windows 10 . Thanks for info . Wondering why Lenovo support is not aware of these fixes ? Wife was on the phone for hours On Thurs. and today and the problem persists .