We know that almost all parts of our brain are somehow involved in our sleep, but there is one peptide that is key: orexin. If orexin-producing cells die, and the switch mechanism between sleep and wakefulness is disabled, it will lead to the disease narcolepsy. Here, the part of the brain involved in narcolepsy is explored using 3D imaging. We can see how the cell projections have gone from the hypothalamus all the way down to the lower brainstem and work closely with the locus coeruleus neurons (red).