The sleep disorders (variable name prefix SLQ) data set provides questions on sleep habits and disorders. The number of questions was expanded to include several questions previously asked in NHANES 2007-2008 (and earlier), and two new questions about usual sleep and wake times.
All participants aged 16 and older were eligible.
Interview Setting and Mode of Administration
These questions were asked in the home, by trained interviewers, using the Computer-Assisted Personal Interview (CAPI) system.
Quality Assurance & Quality Control
The CAPI system is programmed with built-in consistency checks to reduce data entry errors.
Data Processing and Editing
Edits were made to ensure completeness, consistency, and analytic usefulness of the data. Audio recordings were reviewed, when possible, to validate both very low and high hours of sleep.
Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues.
SLQ300 (usual time to sleep) and SLQ310 (usual wake time): formatted as character variables (HH:MM) and written in the 24 hour notation form where HH (00 to 23) is the number of full hours that have passed since midnight and MM (00 to 59) is the number of full minutes that have passed since the last full hour.
SLD012 (hours of sleep) was calculated from questions on usual “fall sleep” and “wake up” times reported during main sleeping period (night or day) for workdays or weekdays (SLQ300 and SLQ310). SLQ012 was rounded to the nearest half hour. Persons who reported that they woke up periodically during their main sleeping period were asked to estimate these times to the best of their ability. As a result SLD012 includes both very short and long sleep durations. If a sleep or wake time was not reported, then SLD012 was not calculated. Note also; SLD012 may not represent the total hours of sleep during a 24 hour period.