Sleep-EDF Database Expanded

Introduction

The sleep-edf database contains 197 whole-night PolySomnoGraphic sleep recordings, containing EEG, EOG, chin EMG, and event markers. Some records also contain respiration and body temperature. Corresponding hypnograms (sleep patterns) were manually scored by well-trained technicians according to the Rechtschaffen and Kales manual, and are also available. The data comes from two studies, briefly described below, and in detail in [1,2].

Data and Annotation Files

The *PSG.edf files are whole-night polysmnographic sleep recordings containing EEG (from Fpz-Cz and Pz-Oz electrode locations), EOG (horizontal), submental chin EMG, and an event marker. The SC*PSG.edf files (see the 'sleep cassette study') often also contain oro-nasal respiration and rectal body temperature.

The *Hypnogram.edf files contain annotations of the sleep patterns that correspond to the PSGs. These patterns (hypnograms) consist of sleep stages W, R, 1, 2, 3, 4, M (Movement time) and ? (not scored). All hypnograms were manually scored by well-trained technicians (identified by the eighth letter of the hypnogram filename) according to the 1968 Rechtschaffen and Kales manual [3], but based on Fpz-Cz/Pz-Oz EEGs instead of C4-A1/C3-A2 EEGs, as suggested by [4]).

All EDF header fields also comply with the EDF+ specs, and unrecorded signals were removed from the ST*PSG.edf files.

The PSG files are formatted in EDF while the hypnograms are in EDF+. The specifications of EDF and EDF+ are on www.edfplus.info and in [5,6]. Each EDF and EDF+ file has a header specifying the patient (in these files anonymized to only gender and age), details of the recording (in particular the recorded time period), and characteristics of the signals including their amplitude calibration.

Sleep Cassette Study and Data

The 153 SC* files (SC = Sleep Cassette) were obtained in a 1987-1991 study of age effects on sleep in healthy Caucasians aged 25-101, without any sleep-related medication [2]. Two PSGs of about 20 hours each were recorded during two subsequent day-night periods at the subjects homes. Subjects continued their normal activities but wore a modified Walkman-like cassette-tape recorder described in chapter VI.4 (page 92) of Bob’s 1987 thesis [7].

Files are named in the form SC4ssNEO-PSG.edf where ss is the subject number, and N is the night. The first nights of subjects 36 and 52, and the second night of subject 13, were lost due to a failing cassette or laserdisk.

The EOG and EEG signals were each sampled at 100 Hz. The submental-EMG signal was electronically highpass filtered, rectified and low-pass filtered after which the resulting EMG envelope expressed in uV rms (root-mean-square) was sampled at 1Hz. Oro-nasal airflow, rectal body temperature and the event marker were also sampled at 1Hz.

Subjects and recordings are further described in the file headers, the descriptive spreadsheet SC-subjects.xls, and in [2].

Sleep Telemetry Study and Data

The 44 ST* files (ST = Sleep Telemetry) were obtained in a 1994 study of temazepam effects on sleep in 22 Caucasian males and females without other medication. Subjects had mild difficulty falling asleep but were otherwise healthy. The PSGs of about 9 hours were recorded in the hospital during two nights, one of which was after temazepam intake, and the other of which was after placebo intake. Subjects wore a miniature telemetry system with very good signal quality described in [8].

Files are named in the form ST7ssNJ0-PSG.edf where ss is the subject number, and N is the night.

EOG, EMG and EEG signals were sampled at 100 Hz, and the event marker at 1 Hz. The physical marker dimension ID+M-E relates to the fact that pressing the marker (M) button generated two-second deflections from a baseline value that either identifies the telemetry unit (ID = 1 or 2 if positive) or marks an error (E) in the telemetry link if negative. Subjects and recordings are further described in the file headers, the descriptive spreadsheet ST-subjects.xls, and in [1].

Software for viewing EDF and EDF+ files

Both EDF and EDF+ formats are free and can be viewed using free software such as:

• Polyman (for MS-Windows only; for details, please follow the link)
• EDFbrowser (for Linux, Mac OS X, and MS-Windows; at www.teuniz.net)
• LightWAVE and the PhysioBank ATM, platform-independent web applications from PhysioNet
• WAVE and other applications for Linux, Mac OS X, and MS-Windows in the WFDB Software Package, also from PhysioNet

An easy way to view these recordings using Polyman is to select File → Open → File(s)... to open a PSG.edf file and its corresponding .Hypnogram.edf file; then select File → Apply Template → Browse... to open SC-cassette.xml (for an SC PSG) or ST-telemetry.xml (for an ST PSG).

Applications using WFDB library version 10.4.5 (February 2008) or later can read EDF files directly with no conversion required. Note that the WFDB library does not decode annotations in EDF+ files, however.

Version History

• Version 0: A small subset of this dataset was previously contributed in 2002 and remains available here for reference and to support ongoing studies.
• Version 1: In 2013, the database was greatly expanded to contain 61 PSGs with accompanying hypnograms.
• Version 2: In March 2018, the database was greatly expanded to contain 197 PSGs with accompanying hypnograms

Database Creator and Contact

Bob Kemp, The Netherlands bk at hsr dot nl

References

1. B Kemp, AH Zwinderman, B Tuk, HAC Kamphuisen, JJL Oberyé. Analysis of a sleep-dependent neuronal feedback loop: the slow-wave microcontinuity of the EEG. IEEE-BME 47(9):1185–1194 (2000)
2. MS Mourtazaev, B Kemp, AH Zwinderman, HAC Kamphuisen. Age and gender affect different characteristics of slow waves in the sleep EEG. Sleep 18(7):557–564 (1995).
3. A Rechtschaffen, AE Kales. A manual of standardized terminology, techniques and scoring systems for sleep stages of human subjects. Los Angeles, CA: UCLA Brain Information Service. Brain Research Institute 10 (1968).
4. B van Sweden, B Kemp, HAC Kamphuisen, EA van der Velde. Alternative electrode placement in (automatic) sleep scoring (Fpz-Cz/Pz-Oz versus C4-A1/C3-A2). Sleep 13(3):279–283 (1990).
5. B Kemp, A Värri, AC Rosa, KD Nielsen, J Gade. A simple format for exchange of digitized polygraphic recordings. Electroencephalography and Clinical Neurophysiology 82:391–393 (1992).
6. B Kemp, J Olivan. European data format 'plus' (EDF+), an EDF alike standard format for the exchange of physiological data. Clinical Neurophysiology 114:1755–1761 (2002).
7. B Kemp. Model-based monitoring of human sleep stages. Ph.D. thesis, Twente University (1987).
8. B Kemp, AJMW Janssen, MJ Roessen. A digital telemetry system for ambulatory sleep recording. In: Sleep-Wake Research in The Netherlands 4, eds ML Coenen and J Arends, Dutch Society for Sleep Wake Research, pp 129–132 (1993).