Chocolate is still associated with...Valentine
Theobromine: Theobromine is to chocolate what caffeine is to coffee; that is to say: the main stimulant. But whilst theobromine INCREASES the heart rate, it DECREASES blood pressure. It’s the “stimulant that relaxes” (note: dogs can’t metabolize chocolate, and it can lead to really unpleasant reactions in them .. so don’t ruin Valentine’s Day by treating your dog)
Phenethylamine (PEA): Phenethylamine works by stimulating the release of endorphins and dopamine. It works the same way as an exercise makes you feel good (and sometimes high). Along with Oxytocin, PEA is also produced in the first flush of love (it also can create migraines in a small number of people .. so you've been warned!)
Trytophan: Trytophan is a chemical that the brain uses to make serotonin, which in high levels can produce feelings of elation, even ecstasy. It can also make you sleepy. And in addition to chocolate, turkey, milk oats and various nuts are also very high in trytophan.
Quercetin: Quercetin is a flavonoid that has anti-inflamatory properties and is claimed to work similarly to Viagra by relaxing blood vessels and increasing blood flow to genitalia. Again, chocolate contains lots of quercitin (as do many other fruits)