Study design: This prospective aEEG study included infants > 32+0 weeks' gestation admitted to the Neonatal Intensive Care Unit at The Royal Children's Hospital in Melbourne who were undergoing major non-cardiac surgery. The BrainZ Monitor (BRM2, Version 8.0, BrainZ Instruments, New Zealand) was applied post-operatively. The time of onset and quality of SWC and the maximum levels of morphine and midazolam as predictors of time to SWC were then assessed.