Typically epileptiform discharges are likely to propagate during NREM sleep along with traditional drowsy EEG arousal periods, as this is a more synchronized state, when we see such synchronized sleep architecture as sleep spindles and high amplitude delta waves. Depending on the stage of sleep, epileptiform discharges can either be activated or inhibited.
There are two main sleep states, nonrapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep.