Dogs can be trained to recognise the minute changes in human behaviour that occur before an epileptic seizure, but such animals are expensive to keep and train. Now, however, Klaus Lehnertz and Christian Elger of Bonn University in Germany have noticed a common pattern in nonlinear brain electrical activity in epileptic patients. Signals produced by the brain decrease in complexity up to several minutes before the onset of a fit (Phys. Rev. Lett. 80 5019).