What do you mean by sitting idle?
In lamp lit LCD screens (most laptops still use these) the lamps take some time to warm up therefore the colour reproduction will be off and underlit compared to normal. This may have the same effect on your machine. My laptop because of the desktop and theme I use has a blue tint when the screen is turned back on after being inactive for a while.
However, LED lit screens do not have this issue as far as I am aware. You need to add more detail to your post as currently there is not enough information to accurately understand the issue.