I am a 23-year-old male, MCA graduate, currently in an exten...

Prompt

I am a 23-year-old male, MCA graduate, currently in an extended job search period with no structured daily routine, high ambient stress, irregular sleep, and long hours of passive screen consumption alternating with intense study sessions. I am not clinically diagnosed with anything. My subjective experience is this: I feel like I have lost the ability to learn and understand itself — not just struggling with hard topics, but the very mechanism of comprehension feels degraded. Concepts that I engage with don't "stick." Reading feels like water passing through a sieve. I can follow sentences but lose the thread of meaning. I feel cognitively blunted rather than sharp. Understanding feels like it requires enormous effort for diminishing returns. I want you to reason through what is likely happening at the molecular and systems neuroscience level — without asking me clarifying questions. Work from the phenomenology I described and reason backward into the biology. Cover the following without skipping depth: synaptic plasticity mechanisms (LTP, LTD, AMPA/NMDA receptor dynamics), the role of BDNF and how its expression is modulated by stress and inactivity, cortisol's structural effects on the hippocampus and prefrontal cortex over weeks of chronic stress, dopaminergic reward prediction and how motivational blunting degrades encoding at the cellular level, the default mode network vs task-positive network competition and what happens when that balance breaks, the role of acetylcholine in attentional gating and why its depletion feels like cognitive fog, glymphatic clearance and what disrupted sleep does to it at the molecular level, and finally metacognition itself — where in the brain the sense of "understanding" is computed and why that signal can degrade independently of raw intelligence. Reason through each layer as a connected system, not isolated facts. Show me how these mechanisms interact and compound each other in a person in my situation. Explain like I'm smart but not a neuroscientist — Feynman-style, first principles, no hand-wavy analogies, actual mechanisms. End with what the neuroscience suggests would most directly reverse this state, ranked by mechanistic evidence strength.