It’s 3:00 PM. You are staring at your computer screen. Your eyelids feel heavy, your focus is gone, and you feel an overwhelming urge to reach for a sugary snack or a third cup of coffee.If this sounds familiar, you aren’t "lazy" and you aren’t alone. As a GP, fatigue is one of the top three complaints I hear in my clinic.But here is the secret: That afternoon crash is usually biology, not burnout. Here is what is actually happening inside your body—and the prescription to fix it.