Have you ever had the misfortune of staying in a hospital for an extended time? The nights are the worst part, aren’t they? It seems like only in hospitals can nights last for SO LONG. If prolonged inactivity and medication weren’t enough to make sleeping difficult, all through the night well-intentioned and hardworking nurses have to come in and flick on the fluorescent lights, which, in older hospitals, flicker to life feebly and cast a greenish light. Wouldn’t it be great if hospitals were a little more optimized for healthy sleep patterns? Lighting, it turns out, may be the key to this kind of improvement.