The sun has an excuse for disappearing at night. The sun gets really tired, same as anyone else – so when night rolls around the sun excuses itself and goes to sleep. It’s a valid excuse.
Since you’re the sun, it’s pretty bright, so before you excuse yourself for the night, you’re wearing Ray-Ban (ばん) sunglasses. You keep these Ray-Ban sunglasses on all day to protect your eyes from being burned by yourself.