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Sleep‐onset stages defined by Hori et al. (1994)
| Sleep stage | EEG stage | Characteristics |
|---|---|---|
| Wake | 1 | Alpha wave train |
| 2 | Alpha wave intermittent (> 50% alpha activity) | |
| Stage 1 | 3 | Alpha wave intermittent (< 50% alpha activity) |
| 4 | EEG flattening | |
| 5 | Ripples | |
| 6 | Hump solitary | |
| 7 | Humps train | |
| 8 | Humps with incomplete spindles | |
| Stage 2 | 9 | Spindles |
Abbreviation: EEG, electroencephalogram.
