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Hispanic Community Health Study / Study of Latinos

Actigraphy introduction

The Sueño Ancillary study recruited 2,252 HCHS/SOL participants to wear wrist-worn actigraphy devices (Actiwatch Spectrum, Philips Respironics) between 2010 and 2013. Participants were instructed to wear the watch for a week. Records were scored by a trained technician at the Boston Sleep Reading Center.

The documentation folder contains manuals and in-depth descriptions of the actigraphy devices and scoring process used in the Sueño Ancillary study. Further, the hchs-sol-sueno-ancillary dataset contains summary phenotype data from the actigraphy data collection.

Epoch-by-epoch files

Epoch-by-epoch (EBE) data files (CSV) have been created for 1,887 participants with actigraphy data whose HCHS/SOL data are available for public use. Each row in these files represents 30 seconds worth of summary data from the actigraphy device. Based upon the Sueño actigraphy scoring, invalid (low quality) days were removed from these files. A day was marked invalid if 1) there were 4 or more hours of offwrist/invalid time or 2) the main sleep period contained offwrist/invalid time.

Notes:

  • The Sueño Ancillary study used actigraphy primarily as a means to estimate sleep and wake times, not as a means to assess physical activity.
  • The day indicator in the file runs from noon-to-noon (i.e. not midnight-to-midnight) because the goal was to have each individual day in the file wholly contain a single main sleep period.
  • Dates have been removed. Each epoch contains a clock time.

Variable description

Each epoch-by-epoch file contains 17 variables. The meanings of these variables are as follows:

Name Label Units / Categories
pid Random BioLINCC ID for LAD
sawa2 Contact Occasion (1 or 2)
line Epoch line number
offwrist Off wrist indicator 0 = On wrist / 1 = Off wrist
activity Activity count
marker Event marker indicator 0 = Marker not pressed / 1 = Marker pressed
whitelight White light Lux
redlight Red light Microwatts per square centimeter
greenlight Green light Microwatts per square centimeter
bluelight Blue light Microwatts per square centimeter
wake Awake indicator* 0 = Asleep / 1 = Awake
interval Interval type*
starth Start hour of recording Administrative variable
day Incrementing day indicator
dayofweek Day of the week 1 = Sunday / 2 = Monday / etc.
validday Valid day indicator Administrative variable
time Clock time HH:MM:SS

* The wake/sleep detection algorithm runs across the entire recording, though sleep in ACTIVE intervals is never counted toward overall sleep totals. Actual sleep is tallied within REST intervals only. REST-S intervals indicate the period between sleep onset and offset.

References

Questions?

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

National Sleep Research Resource
Hispanic Community Health Study / Study of Latinos