Keywords: Sleep EEG Stage 4.jpg This is a screen shot of a patient during Slow Wave Sleep when he is snooring stage 3 The high amplitude EEG is highlighted in red This screen shot represents a 30 second epoch 30 seconds of data Public domain from the English Wikipedia http //en wikipedia org/wiki/Image SWS jpg en wikipedia MrSandman Polysomnography Electroencephalogram Sleep stages |