Photosystem II, a crucial part of plant cells, can be damaged by too much light. Scientists studied how light stress affects the D1 protein in Photosystem II using spinach thylakoids. They found that excessive light causes the thylakoids to unstack, which helps repair damaged D1 proteins. Stacked thylakoids are more prone to damage than unstacked ones, leading to higher levels of harmful hydroxyl radicals. Unstacking thylakoids plays a key role in protecting the D1 protein and aiding in its degradation under light stress.