• Component Description
• Eligible Sample
• Interview Setting and Mode of Administration
• Quality Assurance & Quality Control
• Data Processing and Editing
• Analytic Notes
• References
• Codebook
  • SEQN - Respondent sequence number
  • SLQ300 - Usual sleep time on weekdays or workdays
  • SLQ310 - Usual wake time on weekdays or workdays
  • SLD012 - Sleep hours - weekdays or workdays
  • SLQ320 - Usual sleep time on weekends
  • SLQ330 - Usual wake time on weekends
  • SLD013 - Sleep hours - weekends
  • SLQ030 - How often do you snore?
  • SLQ040 - How often do you snort or stop breathing
  • SLQ050 - Ever told doctor had trouble sleeping?
  • SLQ120 - How often feel overly sleepy during day?

National Health and Nutrition Examination Survey

2017-March 2020 Data Documentation, Codebook, and Frequencies

Sleep Disorders (P_SLQ)

Data File: P_SLQ.xpt

First Published: July 2021

Last Revised: NA

Component Description

The NHANES program suspended field operations in March 2020 due to the coronavirus disease 2019 (COVID-19) pandemic. As a result, data collection for the NHANES 2019-2020 cycle was not completed and the collected data are not nationally representative. Therefore, data collected from 2019 to March 2020 were combined with data from the NHANES 2017-2018 cycle to form a nationally representative sample of NHANES 2017-March 2020 pre-pandemic data. These data are available to the public. Please refer to the Analytic Notes section for more details on the use of the data.

The sleep disorders (SLQ) data set has questions on sleep habits and disorders. Questions on the sleep time and awake time were adapted from the Munich ChronoType Questionnaire (Roenneberg et al., 2003). 

Eligible Sample

All participants aged 16 and older in the NHANES 2017-March 2020 pre-pandemic sample 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 limited built-in consistency checks to reduce data entry errors. Additional edits were conducted post-data collection as described in “Data Processing and Editing.”

Data Processing and Editing

Edits were made to ensure completeness, consistency, and analytic usefulness of the data. Approximately 3% of audio recording interviews were reviewed to validate unusual times for SLQ300, SLQ310, SLQ320, SLQ330 resulting in very long or short hours of sleep.
The most common entry errors were confusing PM and AM hours; (i.e., 12 PM instead of 12 AM), and the transposition of digits when minutes were recorded (i.e., ‘03’ for ‘30’). Comments from interviewers also were considered. Edits were made to approximately 45% of the reviewed records. Summary variables for usual number of hours of sleep on weekdays (SLD012) and weekends (SLD013) were derived from reported times. Hours were rounded to the nearest half hour. For SLD012 and SLD013, very low and high sleep hours were recoded as ‘less than 3 hours’ and ‘14 hours or more.’ For these participants, reported times in SLQ300, SLQ310, SLQ320, SLQ330 were set to “missing” to minimize disclosure risks.

Analytic Notes

The COVID-19 pandemic required suspension of NHANES 2019-2020 field operations in March 2020 after data were collected in 18 of the 30 survey locations in the 2019-2020 sample. Because the collected data from 18 locations were not nationally representative, these data were combined with data from the previous cycle (2017-2018) to create a 2017-March 2020 pre-pandemic data file. A special weighting process was applied to the 2017-March 2020 pre-pandemic data file. The examination sample weights in the demographic data file should be used to calculate estimates from the combined cycles. These sample weights are not appropriate for independent analyses of the 2019-2020 data and will not yield nationally representative results for either the 2017-2018 data alone or the 2019-March 2020 data alone. Please refer to the NHANES website for additional information for the NHANES 2017-March 2020 pre-pandemic data, and for the previous 2017-2018 public use data file with specific weights for that 2-year cycle.

SLD012 (hours of sleep weekdays)/workdays) and SLD013 (hours of sleep weekends/non- workdays): These are derived variables, calculated from reported usual bed time (SLQ300 and SLQ320) and wake time (SLQ310 and SLQ330) during main sleeping period (night or day). Respondents reporting that they woke up periodically or that they slept for very short periods of times at night or during the day were asked to report hours of their main sleeping period. Therefore, SLD012 and SLD013 may not represent the total hours of sleep during a 24 hour period, including naps or other periods of sleep. If either sleep and wake time was not reported, then SLD012 was not calculated. See “Data Processing and Editing” regarding the coding of short or long hours of sleep.

Please refer to the NHANES Analytic Guidelines and the online NHANES Tutorial for further details on the use of sample weights and other analytic issues.

References

• Roenneberg T, Wirz-Justice A, and Merrow M (2003) Life between clocks: daily temporal patterns of human chronotypes. J Biol Rhythms 18:80-90.

Codebook and Frequencies