Wake Up  

How do I wake up Windows 10 if it goes into Hibernate or sleep after a period of in activity

Press a key on the keyboard, move the mouse, or press the power button and release. Don't hold the power button that will shut down the system.

Still not working I had to press & hold the power button. I am a new User of Win 10 on a brand new machine and am a bit sceptical

I see, I usually disable hibernate and sleep. You can check the advanced power options. Do you know how to get to those? If possible find the option that says "Choose what the power buttons do" its on a left pane in the power options. Once you go in there scroll down to the bottom and check to see if the Shutdown settings are enabled or not. There's four of them, Fast Startup (I had to turn mine off, it was the cause of my gpu throttling back and never going full power), followed by Sleep, Hibernate, and Lock. Make sure hibernate and sleep are enabled if you plan on using them.