Stage N2 sleep: Spindle

This image demonstrates a 30-second recording (Compumedics) of stage N2 sleep. Most notable is the beta-frequency spindle activity (dashed box), maximally seen in the central EEG leads. The top two leads represent the eyes (right and left), the next lead is the chin, then the following six leads are EEG (right and left frontal, central, and occipital), ECG with heart rate below (R-R), and the leg EMG lead.