Table 1 Rechtschaffen and Kales sleep staging criteria[10]
From: A transition-constrained discrete hidden Markov model for automatic sleep staging
Sleep Stage | Scoring Criteria |
|---|---|
Wake | When the subject closes their eyes, >50% of the page (epoch) consists of alpha (8–13 Hz) activity or low-voltage, mixed (3–7 Hz) frequency activity. |
Stage 1 | 50% of the page (epoch) consists of related low-voltage mixed (3–7 Hz) activity. Slow rolling eye movements lasting several seconds are often observed in early stage 1. |
Stage 2 | Appearance of sleep spindles and/or K complexes and <20% of the epoch may contain high-voltage (>75 μV, <2 Hz) activity. Sleep spindles and K complexes must each last >0.5 seconds. |
Stage 3 | 20%-50% of the epoch consists of high-voltage (>75 μV), low-frequency (<2 Hz) activity. |
Stage 4 | >50% of the epoch consists of high-voltage (>75 μV, <2 Hz) delta activity. |
Stage REM | Relatively low-voltage mixed frequency EEG with episodic rapid eye movements and absent or reduced chin EMG activity. |