Yet when it comes to scratching all of those dry patches, something inside our brains signals when it’s time to stop. Outside of winter, chronic itch affects millions of people with conditions including eczema, psoriasis, and kidney disease. Understanding the precise biological mechanisms that regulate itch—including what tells us to stop scratching before we get hurt—could help scientists develop better treatment. Instead, it helps trigger a negative feedback signal in sensory neurons that tells the spinal cord and brain that the scratching has been enough and it’s time to stop. “Future therapies may need to be much more targeted—perhaps acting only in the skin, without interfering with the neuronal mechanisms that tell us when to stop scratching,” said Gualdani.