Hey Twibbz -
It sort of sounds like you are wanting something a kin to a day night cycle or at least teh ability to dramatically change from really dark to really light. I would suggest going into your blueprint and actively setting the Auto Exposure settings with a Make Post Process Settings node. Don’t be afraid of that node you only need to work with 2 settings brightness and min brightness. The Nighttime look should be maybe an 8 and 8 and then 1 and 1 for the daytime assuming of course you do not want any eye adaption.
Thank You
Ketchum