Every September, around the time the school buses reappear and the morning air gets that first cool edge, I put a reminder on my calendar that reads like a riddle: “The sun is leaving. Act accordingly.” My husband thinks it’s dramatic. My clients think it’s funny. My bloodwork disagrees with both of them. Here’s the part most people never learn: the sunlight that returns after Labor Day is not the same sunlight. The equinox is a week out, we’re hemorrhaging daylight at close to three minutes a day here in the Northeast, and the sun is arcing lower across the…