The Sleep Heart Health Study (SHHS) is a prospective cohort study designed to investigate the relationship between sleep disordered breathing and cardiovascular disease.

Data Description

Participants were recruited from nine existing epidemiological studies in which data on cardiovascular risk factors had been collected previously. The "parent" cohorts include:

• the Framingham Offspring Cohort
• the Hagerstown and Minneapolis/St. Paul sites of the Atherosclerosis Risk in Communities (ARIC) study
• the Hagerstown, Sacramento and Pittsburgh sites of the Cardiovascular Health Study (CHS)
• the Strong Heart Study sites in South Dakota, Oklahoma, and Arizona
• studies of respiratory disease in Tucson and of hypertension in New York

From these parent cohorts, a sample of participants who met the inclusion criteria (age 40 years or older; no history of treatment of sleep apnea; no tracheostomy; no current home oxygen therapy) was invited to participate in the baseline examination of the SHHS, which included an initial polysomnogram (SHHS-1). Several cohorts over-sampled snorers in order to increase the study-wide prevalence of sleep-disordered breathing. In all, 6441 individuals were enrolled between November 1, 1995 and January 31, 1998. During exam cycle 3 (January 2001- June 2003), a second polysomnogram (SHHS-2) was obtained in 3295 of the participants. Full details of the study design and cohort are found in [1, 2]

Polysomnograms were obtained in an unattended setting, usually in the homes of the participants, by trained and certified technicians. The recording montage consisted of:

• C3/A2 and C4/A1 EEGs, sampled at 125 Hz
• right and left electrooculograms (EOGs), sampled at 50 Hz
• a bipolar submental electromyogram (EMG), sampled at 125 Hz
• thoracic and abdominal excursions (THOR and ABDO), recorded by inductive plethysmography bands and sampled at 10 Hz
• “airflow” detected by a nasal-oral thermocouple (Protec, Woodinville, WA), sampled at 10 Hz
• finger-tip pulse oximetry (Nonin, Minneapolis, MN) sampled at 1 Hz
• ECG from a bipolar lead, sampled at 125 Hz for most SHHS-1 studies and 250 Hz for SHHS-2 studies
• Heart rate (PR) derived from the ECG and sampled at 1 Hz
• body position (using a mercury gauge sensor)
• ambient light (on/off, by a light sensor secured to the recording garment)

The full details of the procedures for obtaining polysomnograms are found in [3].

In this database, each record is represented by several files:

• record.dat - binary signal file
• record.hea - the polysomnogram, in PhysioBank format; the age, sex, and body mass index (BMI) of the subject are specified in the .hea file
• record.edf - the polysomnogram, in European Data Format
• record.hypn - hypnogram (sleep stages, recorded for each 30-second epoch), in PhysioBank annotation file format
• record.arou - EEG arousal events, in PhysioBank annotation file format
• record.resp - respiratory events, in PhysioBank annotation file format
• record.oart - oximeter artifacts, in PhysioBank annotation file format
• record.comp - composite annotation file, containing all annotations from the hypn, arou, resp, and oart files

Details about the contents of the five annotation files can be found here.

The chart included shows a five-second excerpt of record 0000 from the SHHS Polysomnography Database. An obstructive apnea ("Ob.A", annotated near the top of the chart) begins during this excerpt; the annotation indicates that the total duration of this event was 15.1 seconds, during which SaO2 dropped by 2% to a minimum level of 95%.

Access to the complete SHHS data set, including all 9736 polysomnograms and additional covariate data, is available from the Sleep Heart Health Study upon special request and approval. Please visit the SHHS web site for details.

The Sleep Heart Health Study is supported by National Heart, Lung and Blood Institute cooperative agreements U01HL53940 (University of Washington), U01HL53941 (Boston University), U01HL53938 (University of Arizona), U01HL53916 (University of California, Davis), U01HL53934 (University of Minnesota), U01HL53931 (New York University), U01HL53937 and U01HL64360 (Johns Hopkins University), U01HL63463 (Case Western Reserve University), and U01HL63429 (Missouri Breaks Research).

The Sleep Heart Health Study acknowledges the Atherosclerosis Risk in Communities Study (ARIC), the Cardiovascular Health Study (CHS), the Framingham Heart Study (FHS), the Cornell/Mt. Sinai Worksite and Hypertension Studies, the Strong Heart Study (SHS), the Tucson Epidemiologic Study of Airways Obstructive Diseases (TES) and the Tucson Health and Environment Study (H&E) for allowing their cohort members to be part of the SHHS and for permitting data acquired by them to be used in the study. SHHS is particularly grateful to the members of these cohorts who agreed to participate in SHHS as well. SHHS further recognizes all of the investigators and staff who have contributed to its success. A list of SHHS investigators, staff and their participating institutions is available on the SHHS web site.

Physionet thanks Susan Redline and Dan Gottlieb of the Sleep Heart Health Study for arranging for these data to be made freely available here.

National Sleep Research Resource

Following a 2003 agreement between SHHS and Physionet to make 1000 polysomnograms from the SHHS-2 examination available freely via PhysioBank, in 2014 the SHHS investigators launched the National Sleep Research Resource (NSRR), which offers free access to much more of the SHHS PSG Database, including clinical data elements not available here.

Users can query and search across thousands of data elements, identify those data of most relevance for given needs, explore the statistical distributions of each, and download the data. Physiologic signals from overnight sleep studies are available as downloadable EDF PSGs. Users can also download standard (Rechtschaffen and Kales or AASM) annotations of these PSGs, and summary measures derived from them. The first data set available includes over 8,000 studies from exams 1 and 2 from the Sleep Heart Health Study, with scheduled new data releases every quarter from additional data sets. NSRR also provides open-source software for viewing and analyzing these data.

References

1. Quan, S.F., et al., The Sleep Heart Health Study: design, rationale, and methods. Sleep, 1997. 20(12): p. 1077–85.
2. Lind, B.K., et al., Recruitment of healthy adults into a study of overnight sleep monitoring in the home: experience of the sleep heart health study. Sleep Breath, 2003. 7(1): p. 13–24.
3. Redline, S., et al., Methods for obtaining and analyzing unattended polysomnography data for a multicenter study. Sleep, 1998: p. 759–767.
4. Whitney, C.W., et al., Reliability of scoring respiratory disturbance indices and sleep staging. Sleep, 1998. 21: p. 749–758.
5. Rechtschaffen, A. and A. Kales, A manual of standardized techniques and scoring system for sleep stages of human subjects. Washington, D.C.: U.S. Government Printing Office, 1968. NIH Publication No. 204.
6. The Atlas Task Force EEG arousals: scoring rules and examples. Sleep, 1992. 15: p. 173–184.