Polysomnography introduction

Sleep studies took place either through normal clinical channels for those recruited from sleep clinics (level 1 polysomnography or level 3 home sleep tests), or administered by the investigators for those recruited from cardiology or diabetes clinics (using either Embletta Gold or Embletta X100, Embla). All studies were scored by a single registered polysomnographic technologist using the American Academy of Sleep Medicine (AASM) alternative hypopnea criteria when arousal data were available, or the AASM recommended criteria when electroencephalographic data were not recorded.

Notes:

• Montage and Sampling Rate Information
• The majority of sleep studies were conducted at home using the Embletta devices. A small subset of studies were collected in laboratory settings.

Signal and annotation files

Raw polysomnography data is available for 152 randomized participants at baseline and 93 at followup. Each recording has a signal file (.EDF) and event scoring (.XML).

1. EDF - Signal files in the European Data Format exported from Compumedics Profusion.
2. XML (Profusion) - Annotation files exported from Compumedics Profusion. (Learn more...)
3. XML (NSRR) - Annotation files processed in the EDF Editor and Translator tool.

NSRR XML files can be overlaid onto EDF signal files using the EDF Viewer tool. For more information about the XML translation (mapping) process, review the files available on the EDF Editor and Translator Releases page.

Hypopnea event tags

Hypopnea events are represented by two different tags in the XML annotation files. Events with the Hypopnea tag are hypopneas with a reduction in airflow between 30% and 50% from baseline levels. Events with the Unsure tag are hypopneas with a reduction in airflow greater than 50% from baseline levels.

If interested in all hypopneas that have a 30% or more reduction in airflow, both event types should be included. If interested in events with greater reduction in airflow (>50%), use those that were labeled with the Unsure tag.

The Unsure tag does not represent uncertainty about the event, but rather was the only custom tag available in the original polysomnography scoring program.

Additional criteria can be applied to limit events based on associated desaturation and/or arousal.

Known issues

• No known issues yet

History / changelog

June 2018

• Polysomnography data uploaded to sleepdata.org

Questions?

Please reach out to us at support@sleepdata.org or in the Forum if you have questions.