“The future is neurochemical,” says Smith of Johns Hopkins. “We can treat apnoea in a mouse. Probably in the next ten years, maybe five, you’ll be able to take medication for sleep apnoea, because it’s a neural-chemical problem. It’s not obesity itself, not fat pressing on the airway, but fat excreting certain hormones that makes the airway collapse.” Schwartz is more circumspect – he thinks “it’s a combination of the two” – but has also been investigating hormones secreted by fat cells.