Turn your sim into a vampire - The sims 3 Late night. First of all you have to befriend a vampire, then you can see when you click the vampire there is an option "Ask to turn", click on it then voila, your sim is now a vampire, but maybe wait for 2 or 3 days to complete the cycle of being a vampire.
Note: your sim will gonna encounter some negative moodlets when you're on the stage of being a vampire. One is nausea. This will affect your sim's mood, and will gonna deduct a happy mood. (the green bar)
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