A period analysis classification of sleep stages.

Abstract The predictive application of a period analysis classification of waking and sleep stages achieved an over-all agreement of 69% with visually classified epochs among eighteen young male subjects. The classification was based upon the number of seconds/20 sec epoch of major period counts in each of three bandwidths: 0–3, 4–7 and 8–30 c/sec. Agreement with stages W (waking), 3 and 4 exceeded the inter-rater (76%) and intra-rater (77%) reliability of visually classified epochs, whereas the identification of stages 1 and 2 was 45% and 63%, respectively. It was proposed that stages 1, 1-REM and 2 might be identified accurately by period analysis of electro-oculogram and electromyogram and by shortening the resolution of 1.0 sec used in this study to 0.5 sec.