Nature, Published online: 05 February 2025; doi:10.1038/d41586-025-00314-wA comprehensive atlas of the human hypothalamus, a brain region that regulates many bodily functions, including temperature, sleep and appetite, has been built using single-cell RNA sequencing and spatial transcriptomics. The atlas reveals previously unappreciated anatomical and cellular diversity, insights into obesity genetics and key therapeutic differences between humans and mice.