What lighting mods are you using? Also, what is your brightness set to? Mine is usually set to 1.25 and I still get it dark enough where the brightest thing in the sky is the New Vegas lights or your average fire barrel. Can you give us your mod list so we can figure out why your nighttime is bright?
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" Life is a beautiful and awesome process, awe-inspiring exchange of living things working together or against each other for each their own purposes." -Me, Matthew.