Does that happen upon a normal shut down and a normal start-up?
--- If that part is ok, your issue should be based on what’s wrong when waking up the computer.
See if either one or both of these ideas make a difference
--- Turn off Hibernate: Command prompt (admin) / powercfg.exe /hibernate off.
--- Go to Advanced system settings > Performance > Settings > Select Adjust for best performance.
--- Go into Device Manager and try to update the graphics driver: I suspect it will tell you that you have the latest driver.
Here are a few more ideas
Check out
Intel® Driver & Support Assistant (Intel® DSA)
Intel® Driver & Support Assistant
Evaluate Intel’s report
Download HP Support Assistant
HP Support Assistant | HP® Official Site
It includes some features such as checking out the computer.
Since the computer is less than 1 year old, ask HP if your issue is covered under their standard warranty.
Although it probably isn’t because their standard warranty usually covers only hardware for the first year, but it wouldn’t hurt to ask.
On the "couple hours" timeframe, it's probably because the HDD has been turned off by that time. When the screen is black, what happens when you wait some period of time such as 5 minutes?