Most of us spend our days under artificial light, starved of the very element that shaped human biology over millennia. The result is a silent epidemic of deficiency that drags down mood, drains energy, disrupts sleep, and weakens immune defenses. This book offers a clear, science-based path back to the light—not through quick fixes, but by understanding how daylight interacts with your body to produce vitamin D, regulate your internal clock, and restore a sense of vitality you may have forgotten was possible. Drawing on decades of research reviewed by major health organizations, Marcus Reed Halloway explains why spending fifteen minutes of morning sun on your skin can be more powerful than any pill, and why even small shifts in your daily light exposure can transform how you feel. You will learn practical strategies for every season and setting: from the office worker in a windowless cubicle to the northern-hemisphere winter dweller. The Vitamin D Prescription is not a medical guide—it is an invitation to treat daylight as the essential nutrient it truly is. Part of The Sagewell Wellness Library.