Review Concludes Polysomnography Tests Should Be Used to Study Socioeconomic Effects on Sleep

In a review published in Clocks and Sleep, a researcher concluded that polysomnography (PSG) tests offered the best opportunity to evaluate the relationship between socioeconomic status (SES) and quality of sleep on an objective level.

The author stated that other sleep studies have used self-reported instruments, like Insomnia Severity Index and Pittsburgh Sleep Quality Index, whereas very few studies in sleep research and health disparities had used objective measurements like PSG in their research.

PSG tests measure the electrical activity of the brain, eye movement, and muscle movement during sleep. They also measure sleep stages and cycles to identify sleep disturbances. The goals of the review were to analyze how sleep health disparities based on SES are measured with PSG in the general population and to suggest improvement for clinical practice.

For this review, 7 studies were selected for inclusion, all cross-sectional. The author identified useful studies by searching the databases of PubMed/MEDLINE and Google Scholar between January 2000 and April 2021. Keywords such as socioeconomic status, sleep, polysomnography, and sleep quality were used to find relevant studies. Studies were excluded if they were interventional trials; if they were not written in English or French; if they did not present original research, did not have the full text accessible, or did not contribute statistical significance on the subject; if their authors recruited participants; or if they used actigraphy instead of PSG.

Of the 7 studies, 3 were from the United States, 2 were from Switzerland, 1 was from India, and 1 was from Brazil. All participants in these 7 studies were adults and represented a global population of 7638 people. Participants were aged 18 to 81 years. SES was identified through education in 5 studies, income in 3 studies, occupation and occupational position in 2 studies, composite score/perceived SES in 2 studies, and employment in 1 study.

Sleep parameters measured in these studies included sleep duration, sleep efficiency, sleep latency, sleep architecture, stage shifts, wake after sleep onset (WASO), sleep continuity, and total sleep time. The duration of PSG readings ranged from 1 to 3 nights.

Findings identified lower SES as being associated with longer sleep latency, more WASO, less sleep efficiency, and higher stage shifts in PSG. Participants with lower childhood SES spent more time in stage 2 sleep and less time in slow-wave sleep than participants with higher childhood SES, regardless of current SES status. Financial strain was significantly correlated with poorer subjective sleep quality and PSG-assessed sleep continuity.

Men with low education level or occupational position were more likely to experience poor sleep quality, short sleep duration, or insomnia. Men with a low occupational position were also more likely to have long sleep latency. Women with low educational level were more likely to have long sleep latency and short sleep duration. They were also more likely to have excessive daytime sleepiness if in a low occupational position.

Women from low childhood SES backgrounds had longer sleep latency than women in the high childhood SES group. One study found that SES affects obstructive sleep apnea (OSA) risk differentially for men and women, with low income acting as a moderator in the relationship between SES and the individual’s sleep. Another study reported that the association between home PSG measures of OSA and SES was mediated by body mass index.

The author stated that this review provided evidence that PSG could be used to find individual differences in sleep health among people with or without a sleeping disorder. PSG studies should always collect data on SES in order to further identify the relationship between SES and sleep quality, the author noted. It may also be possible to study those SES indicators and sleep quality over time.

The review identified SES as having an impact on objective sleep measurement. However, the author noted that all the studies used were conducted in developed countries. Studies conducted in developing countries were needed to draw a meaningful conclusion on the relationship between SES and sleep quality.

The review concluded that PSG provided more useful details that can objectively indicate sleep health disparities with more accuracy than subjective assessments. Classes on using PSG should be provided for researchers and students in order to increase PSG utilization in sleep studies, the author wrote, and prices of the testing devices should be kept reasonable by manufacturers to ensure accessibility.

Reference

Etindele Sosso FA. Measuring sleep health disparities with polysomnography: a systemic review of preliminary findings. Clocks Sleep. 2022;4(1):80-87. doi:10.3390/clockssleep4010009