Why does my motivation vanish every afternoon at work, even though mornings are fine?

Lately, I've been noticing this weird pattern where my energy and motivation at work just tank every afternoon. Mornings are actually pretty productive - I get my emails done, attend meetings, and even brainstorm new ideas. But come 2 or 3 PM, I hit this wall where I feel drained and distracted, no matter how much coffee I’ve had or how many breaks I take. I've tried adjusting my lunch timing and even swapped to lighter afternoon tasks, but it doesn’t seem to help. I work in a mostly quiet office with natural light, so I’m not sure if it’s the environment or something else. This slump is frustrating because I want to keep the momentum going throughout the day without feeling like I’m dragging myself through it. Has anyone else experienced this afternoon crash? What strategies have helped you push through or prevent it? Also, could it be related to my diet or sleep, and how would I figure that out without making too many drastic changes all at once?