I think it may be from lying down at night. This would cause fluids to flow up to your face/head region, whereas during the day, whilst sitting or standing, body water gravitates more down to the legs.
The body water fills more of the facial skin and scars seem less pronounced. That's my hypothesis anyway. If correct, what it means is that drinking lots of water will help and also, lying down for an hour's afternoon nap may also help a little.
All the Best.
The above is only my Personal Humble Opinion, Folks.
I am no expert on these matters. Please consult the (supposed) experts, and seek the advice of other people as well.