Hawaii - Nightlife

If you're the sort of person who doesn't come alive until after dark, you're going to be pretty lonely on the Big Island. Blame it on the plantation heritage. People did their cane-raising in the morning. 
Nevertheless there are things to do at night if you ask around, and certainly your hotel will have activities. Movies and a small theater scene do keep locals happy, and if you want details on either one ask your concierge or pick up a local paper and look for listings.