I'll occasionally brew a cup of decaf or half-caf if I'm looking for a small perk in the evening but don't want to risk being up too late. Possibly an addiction

I'll occasionally brew a cup of decaf or half-caf if I'm looking for a small perk in the evening but don't want to risk being up too late. Possibly an addiction thing (pavlov's bitter brew?) or possibly just the nature of the bitter flavor.