In-home polysomnography (PSG) was conducted using the Compumedics Somte System (Compumedics Ltd., Abbotsford, Australia). The sensors and recording montage consisted of cortical electroencephalograms (central C4-M1, occipital Oz-Cz, and frontal Fz-Cz leads), bilateral electrooculograms, chin EMG, thoracic and abdominal respiratory inductance plethysmography (by auto-calibrating inductance bands); airflow (by nasal-oral thermocouple and pressure recording from a nasal cannula); ECG; leg movements, and finger pulse oximetry. In addition to connection of sensors and electrodes, trained staff members completed signal calibrations and checked impedance. Nocturnal recordings were transmitted to the centralized reading center at Brigham and Women's Hospital and data were scored by trained technicians using current guidelines.
Raw polysomnography data are available for 2,056 MESA Sleep participants. Each recording has a signal file (.EDF) and two versions of the event scoring and epoch staging annotations (.XML).
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 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 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.