Narcolepsy is a neurological condition featuring sudden bouts of sleep and muscle weakening that disrupt patients’ everyday function. Current treatments have unpleasant side effects. People with narcolepsy lack a wakefulness peptide known as hypocretin in their brains, but no drugs exist to replace this missing compound. Now, a team led by Jerome Siegel at the University of California, Los Angeles, has demonstrated that 14 days of morphine treatment restores the number of hypocretin-producing neurons in mice with a condition mimicking narcolepsy, rousing the animals and reducing their muscle weakening (Sci. Transl. Med. 2018, DOI: 10.1126/scitranslmed.aao4953). The researchers say that rather than morphine, which is an opiate, nonaddictive opiate-like compounds may be used to treat narcolepsy one day, but more work is needed. The team pursued this line of research because earlier, they had found that brains from people who use heroin chronically had 54% more hypocretin neurons on average than the control group. That finding suggests there might be a link between the hypocretin system and opioid addiction, Siegel says.