As we move just beyond the shortest day of the year, many people are still feeling the effects of the long, dark stretch of winter—mood dipping, energy waning, and sleep feeling just a little more fragile. It’s no coincidence. Human beings are designed—biologically, ancestrally, and energetically—to live in partnership with natural light. Long before modern life, our ancestors rose with the sun, spent their days outdoors, and wound down with the sunset. Our bodies still carry