Example confounds to spindle detection introduced by sharp features in the EEG. A, Spindles (thick arrows) in the EEG (black) increase the magnitude of σ activity computed using the wavelet transform (orange). B, C, Abrupt increases in the EEG at (B) epileptiform spikes (thin arrows); and (C) the sharp negative deflection in a K-complex (short arrow) increase the magnitude of σ activity. D, The average median wavelet σ power increases with spike rate in CECTS patients (red circles). Black line indicates model fit.