The reasoning: two adaptation mechanisms
Dark adaptation (threshold falls ~10⁶‑fold over ~30–40 min): cone branch plateaus within ~5–10 min; rod–cone break ~7–10 min; rod branch continues as rhodopsin regenerates via the RPE retinoid cycle (all‑trans‑retinol → RPE → LRAT, RPE65 isomerohydrolase → 11‑cis‑retinal). Cones regenerate faster and also use a Müller‑glial pathway. Light adaptation (seconds): Ca²⁺‑dependent feedback (GCAPs, recoverin), pigment bleaching, pupil constriction, network gain changes.