Annotation files
Use the PhysioBank ATM (or any PhysioToolkit application) to read the annotation files included in the SHHS Polysomnography Database. The text strings associated with each annotation are described below.
Return to the SHHS PSG Database
Hypnogram (.hypn) annotations
The text strings indicate the sleep stage for the following 30-second epoch, according to this scheme:
| code | meaning |
|---|---|
| W | subject is awake |
| 1 | sleep stage 1 |
| 2 | sleep stage 2 |
| 3 | sleep stage 3 |
| 4 | sleep stage 4 |
| R | REM sleep |
EEG arousal (.arou) annotations
The text strings contain the following information:
- Event type (Arousal)
- Duration in minutes, seconds, and tenths of seconds (m:ss.s)
Respiratory event (.resp) annotations
The text strings contain the following information:
- Event type (Hyp: hypopnea; Ob.A: obstructive apnea; Cn.A: central apnea)
- Duration in minutes, seconds, and tenths of seconds (m:ss.s)
- Percent decrease in SaO2 associated with the event
- Minimum SaO2 (percent) associated with the event
Oximeter artifact (.oart) annotations
The text strings contain the following information:
- Event type (SaO2.Art)
- Duration in minutes, seconds, and tenths of seconds (m:ss.s)
Composite (.comp) annotations
The composite annotation file for each record contains all of the annotations in the .hypn, .arou, .resp, and .oart annotation files. These can always be distinguished by the event type (or sleep stage, in the case of the .hypn annotations). In addition, the chan field of the annotations, which appears in the fifth column of rdann's output, indicates the source of each annotation, according to this scheme:
| code | meaning |
|---|---|
| 0 | sleep stage (.hypn) |
| 1 | EEG arousal (.arou) |
| 2 | respiratory event (.resp) |
| 3 | oximeter artifact (.oart) |
Return to the SHHS PSG Database