Your brain has been making its own cannabis since the day you were born.

In 1992, scientists isolated a compound no one had seen before. They named it anandamide, from the Sanskrit word for bliss. It turned out to be the brain's own version of the active ingredient in cannabis, released naturally during deep focus, hard exercise, and flow states.

The discovery solved a puzzle that had confused researchers for years. Long before anandamide was found, scientists already knew the brain was lined with receptors built to receive THC, the active compound in cannabis. 

That was strange. 

Why would the brain evolve docking stations for a compound made by a plant?

The answer: those receptors were never built for THC in the first place. They were built to receive anandamide, the brain's own molecule. THC just happens to be shaped closely enough to anandamide that it can dock at the same receptors and switch them on too. The plant didn't create the connection. It stumbled into equipment the brain already had.

Then came a detail almost nobody saw coming. Dark chocolate contains compounds that mimic anandamide, plus others that slow its natural breakdown, stretching out the bliss a little longer.

Which might be the most scientifically defensible excuse yet for keeping a bar in your desk drawer.