HP Pavilion g7 - Screen contrast adjusting itself

HP Pavilion g7 - Screen contrast adjusting itself

I can't really think of any reason as to why this would happen, but lately
my laptop has been acting a bit odd. It is an HP Pavilion g7 2017cl.
This has happened now twice - the screen will slowly (over a period of
about 10 seconds) fade into a much higher contrast that's really annoying
to look at. The only explanation is that I hibernate my computer a lot
instead of shutting down/restarting.
It seems to be fixed after a restart, but obviously I'd like to fix the
main problem instead of just making it go away for a week.