Abstract
Objective:
To investigate correlates of restless sleep among street-based female sex workers (FSW) in the U.S., an understudied population experiencing high rates of structural vulnerabilities (e.g., homelessness, food insecurity) and trauma.
Methods:
Using data from a cohort of street-based cisgender FSW (n=236; median age=35 years, 68% Non-Hispanic White), we examined cross-sectional associations of individual, interpersonal, and structural factors with frequent restless sleep over the past week (5–7 vs. <5 days).
Results:
Participants reported a high prevalence of homelessness (62%), food insecurity (61%), daily heroin injection (53%), lifetime sexual or physical violence (81%), and frequent restless sleep (53%). Older age, food insecurity, poor self-rated health, and cumulative violence exposure were independently associated with frequent restless sleep.
Conclusion:
Frequent restless sleep was prevalent among FSW with higher odds among those experiencing intersecting vulnerabilities and multiple exposures to violence. Further research on sleep health in this population is needed to understand its role in health risks.
Keywords: restless sleep, street-based female sex workers, violence, trauma, structural vulnerability
Introduction
Poor sleep is a significant public health concern and is bidirectionally associated with several physical and psychiatric health conditions.1 For example, insomnia - characterized by trouble falling or staying asleep, poor sleep quality, restless sleep, or nonrestorative sleep2 - is highly prevalent3 in the United States, with higher rates and severity documented among older adults,4 women,5 and racial minorities.6 A growing body of evidence highlights sleep challenges among structurally vulnerable populations - those who face constrained resource access due to their position within social, economic, and political structures7 - such as people who use drugs,8 police- and violence-exposed populations,9,10 and those who experience food11 and housing12 insecurity.
We know of no research examining sleep among street-based female sex workers (FSW), a population who experiences many of these vulnerabilities concurrently, with their impact amplified because they operate in physical and social environments posing unique challenges to sleep.13,14 Like shift workers in other sectors, FSW who work at night or in the early morning may be at risk for chronic health conditions, accidents, and cognitive impairment.15 In addition, trauma is prevalent among FSW, who have post-traumatic stress disorder (PTSD) severity comparable to war veterans.16 Many are exposed to sexual or physical violence in childhood and revictimized by clients, intimate partners, and law enforcement as adults.16 FSW experiencing homelessness may face increased exposure to violence,12 and the interplay of violence, police exposure, and housing and food insecurity may impact FSW’s ability to benefit from restful sleep. Substance misuse is also prevalent among FSW and has a bidirectional relationship with poor sleep, potentially compounding these barriers to sleep.8 This exploratory study aimed to characterize associations of individual, interpersonal, and structural factors with frequent restless sleep among FSW in Baltimore City, Maryland.
Methods
Participants and Procedure
We used baseline data from the Sex Workers and Police Promoting Health in Risky Environments (SAPPHIRE) study, a year-long observational prospective cohort study of FSW’s HIV risk environment in Baltimore, Maryland. 250 cis- and transgender street-based FSW were recruited through targeted sampling in 14 zones between April 2016 and January 2017, as detailed previously.17 Eligibility criteria included age 15+, sold or traded oral, vaginal, or anal sex “for money or things like food, drugs, or favors,” picked up clients in public places 3+ times in the past 3 months, and willingness to undergo HIV/STI testing. Exclusion criteria included identifying as a male/man. Participants completed a 50-minute computer-assisted personal interview (CAPI) with an interviewer who provided appropriate referrals and financial compensation. The study was approved by the Johns Hopkins Bloomberg School of Public Health Institutional Review Board. This analysis included cisgender FSW with complete data in the final model (N=236); about 5% of total participants refused to answer questions on violent experiences.
Measures
Sleep.
Respondents indicated the number of days in the past week that their sleep was restless (<1 day [16%], 1–2 [14%], 3–4 [17%], 5–7 [53%]) in an item from the Center for Epidemiologic Studies Depression Revised-10 (CESD-10) Scale.18 Due to the high prevalence of 5–7 days of restless sleep, responses were collapsed into a binary variable (frequent: 5–7 days vs. less frequent: 0–4 days).
Individual correlates.
Age (<35 vs. 35+, split at median) and sexual orientation (sexual minority vs. heterosexual) were dichotomized; race (non-Hispanic White, non-Hispanic Black, Hispanic/Other) was trichotomized. Daily substance use and mode of administration over the past 3 months (subsequently termed “recent”) were analyzed as binary variables. Binge drinking (4+ drinks on one occasion) within the past year was measured with the Alcohol Use Disorders Identification Test-Concise (AUDIT-C)19 and dichotomized (daily or almost daily vs. less frequent). Participants rated their general health from poor to excellent; responses were dichotomized (poor vs. higher ratings). PTSD symptoms were measured with the PTSD Checklist for Diagnostic and Statistical Manual of Mental Disorders - Fifth Edition (PCL-5)20 and dichotomized (scores ≥33 [probable PTSD] vs. <33).
Interpersonal correlates.
Violence was measured by an adapted Revised Conflict Tactics Scale.21 Childhood violence was measured as ever being pressured or forced into sexual intercourse or touching (sexual violence: yes/no) or being physically hurt by someone causing injury (physical violence: yes/no) before age 18. We measured adulthood violence separately for four common perpetrators: intimate partners; sex work clients; police officers; and pimps/managers. Sexual violence was defined as ever being physically forced to have vaginal or anal sex (yes/no); physical violence was defined as ever being physically hurt by or threatened with punching, slapping, hitting, or use of a weapon (yes/no). Cumulative violence, defined as the sum of each type of lifetime violence, was constructed as a 3-level categorical variable (0, 1–2, and 3–4 experiences) and used as our violence measure.
Structural correlates.
Education (non-high school graduate vs. higher), food insecurity (recently went to bed hungry 1+ night per week vs. 0), and housing insecurity (recently lived in 3+ places vs. fewer) were dichotomized. Current homelessness was analyzed as a binary variable (yes/no).
Analysis
Initial variables of interest were selected a priori based on theory, literature, and exploratory interest. Pearson’s χ2 tests were used to assess differences by restless sleep frequency; variables significant at the p<.05 level were considered for model inclusion. We used multivariable logistic regression with variance clustered for geographic recruitment zone to examine correlates of frequent restless sleep. PTSD severity and cumulative violence were highly colinear; we retained cumulative violence in the final model because the PCL-5 contains sleep items. All analyses were conducted using Stata/SE 15.1 (StataCorp, College Station, TX).
Results
Descriptive analysis
The median age was 35 years and 68% identified as non-Hispanic white (Table 1). Daily substance misuse was prevalent (53% heroin injection, 61% crack use). Thirty women (13%) rated their physical health as poor. Most experienced violence in childhood (35% sexual, 42% physical) or adulthood (39% sexual, 72% physical) and 62% screened positive for PTSD. Participants were highly structurally vulnerable (52% lacked a high school diploma, 62% recently homeless, 55% recently housing insecure, and 61% weekly food insecurity).
Table 1:
Baseline factors associated with restless sleep among female sex workers in Baltimore, Maryland, 2016–2017 (N=236)
| Restless sleep past week: 5–7 days | |||
|---|---|---|---|
| Total | No | Yes | pb |
| N=236 | 111 (47.0) | 125 (53.0) | |
| n (col%)a | n (col%) | n (col%) | |
| 120 (50.8) | 67 (60.4) | 53 (42.4) | 0.006 |
| 116 (49.2) | 44 (39.6) | 72 (57.6) | |
| 160 (67.8) | 72 (64.9) | 88 (70.4) | 0.344 |
| 52 (22.0) | 29 (26.1) | 23 (18.4) | |
| 24 (10.2) | 10 (9.0) | 14 (11.2) | |
| 168 (74.7) | 77 (72.0) | 91 (77.1) | 0.375 |
| 126 (53.4) | 57 (51.4) | 69 (55.2) | 0.554 |
| 144 (61.0) | 62 (55.9) | 82 (65.6) | 0.126 |
| 19 (8.1) | 9 (8.1) | 10 (8.0) | 0.976 |
| 30 (12.7) | 6 (5.4) | 24 (19.2) | 0.001 |
| 135 (61.6) | 48 (45.7) | 87 (76.3) | 0.000 |
| 110 (46.6) | 52 (46.8) | 58 (46.4) | 0.945 |
| 96 (40.9) | 38 (34.5) | 58 (46.4) | 0.065 |
| 82 (34.7) | 30 (27.0) | 52 (41.6) | 0.019 |
| 92 (39.0) | 38 (34.2) | 54 (43.2) | 0.159 |
| 100 (42.4) | 38 (34.2) | 62 (49.6) | 0.017 |
| 169 (71.6) | 70 (63.1) | 99 (79.2) | 0.006 |
| 45 (19.1) | 30 (27.0) | 15 (12.0) | 0.007 |
| 106 (44.9) | 49 (44.1) | 57 (45.6) | |
| 85 (36.0) | 32 (28.8) | 53 (42.4) | |
| 122 (51.7) | 58 (52.3) | 64 (51.2) | 0.872 |
| 146 (61.9) | 69 (62.2) | 77 (61.6) | 0.929 |
| 128 (54.5) | 60 (54.1) | 68 (54.8) | 0.904 |
| 143 (60.6) | 56 (50.5) | 87 (69.6) | 0.003 |
Column percent.
Pearson’s χ2 test.
Over half of FSW (53%) reported frequent restless sleep. Frequent restless sleep was more common among those who were age ≥35 years (p=0.006), had poor self-rated health (p=0.001), scored ≥33 on the PCL-5 checklist (p<.0001), experienced childhood sexual (p=0.019) or physical (p=0.017), or adulthood physical (p=0.006) violence, and experienced weekly food insecurity (p=0.003). FSW without violence exposure histories were less likely than those with one or more traumas to report frequent restless sleep (p=0.007). Remaining variables were not significantly associated with the outcome.
Multivariable Logistic Regression
In a model containing all significant correlates, age ≥35 years (adjusted odds ratio (aOR): 2.67, 95% CI: 1.64, 4.36, p<.0001; Figure 1), self-rated poor health (aOR: 3.98, 95% CI: 1.99, 7.96, p<.0001), and weekly food insecurity (aOR: 2.02, 95% CI: 1.42, 2.88, p<.0001) were independently associated with frequent restless sleep. Results also supported a dose-response relationship between cumulative violence and frequent restless sleep (aOR 1–2 experiences: 2.38, 95% CI: 1.43, 3.99, p=0.001; aOR 3–4 experiences: 3.67, 95% CI: 2.22, 6.05, p<.0001). To more closely approximate the diagnostic criteria for insomnia disorder (≥3 nights of sleep difficulty per week),22 we conducted an additional analysis comparing 3–7 days of restless sleep to fewer; findings remained consistent. As a sensitivity analysis, we also ran the same model with a binary PCL-5 sleep item as the outcome (trouble falling/staying asleep within the past month: extremely or quite a bit [51%] vs. less); only the effects of cumulative violence and weekly food insecurity remained significant [data not shown].
Figure 1.
Adjusted odds of restless sleep among female sex workers in Baltimore, Maryland, 2016–2017 (N=236)
Discussion
In the first known study of sleep among FSW, our findings suggest that street-based FSW, like other structurally vulnerable groups,8,9,11,12 experience high levels of sleep disturbance and concurrent vulnerabilities that may amplify risk for poor sleep and its health effects. Consistent with findings in other populations, we identified associations of older age,4 food insecurity,11 and self-rated poor health23 with restless sleep. The pervasiveness of trauma among FSW and its association with restless sleep highlights yet another challenge to wellbeing in this population.10,13,14,16
Numerous studies document the physical, social, economic, and policy risks that shape harms among vulnerable groups.24 In addition to the factors we identified, multiple aspects of FSW’s daily lives - including substance use, housing insecurity, and sex work illegality - may adversely affect sleep. FSW experiencing homelessness may not benefit from shelters, many of which are closed during the day when FSW may be sleeping. Because sex work remains illegal and stigmatized in the U.S., FSW also face barriers to healthcare, social services, and drug treatment;13 such marginalization may exacerbate other issues degrading sleep quality. Poor sleep may diminish attention and aspects of executive function, including inhibition, that may promote risky behavior.25 For FSW, this may also result in reduced ability to negotiate condom use with clients or to recognize signs of an overdose. Further research is needed in this domain.
Limitations of the current study include the lack of information on FSW’s specific working or sleeping hours and the use of a single item from the CESD-10 scale to measure only one dimension of sleep. While this item was likely designed to capture insomnia as a depressive symptom, it could also reflect sleep disorders such as restless legs syndrome and sleep-disordered breathing, or unmeasured aspects of the sleep environment. In addition, findings reflect a local, urban sample in a single state and may not generalize to other locales. However, this is a first step in examining sleep health in FSW. Few studies on sleep health have included populations such as FSW, who are unstably housed or disconnected from health care. Further, many existing instruments used in sleep research and recommendations for sleep carry implicit assumptions about sleeping schedules and environments that may not apply to structurally vulnerable populations, such as sleeping at night or in a bed.
Restful sleep is a fundamental human need that our findings suggest is unmet among urban, street-based FSW. Our sample exhibited a high prevalence of frequently restless sleep, with amplified risk among those with intersecting vulnerabilities and multiple exposures to violence. Improving sleep may confer physical, mental, and cognitive benefits that help FSW address their other concerns. Future prospective studies applying objective and expanded subjective sleep measures tailored for FSW, as well as research examining the extent to which FSW’s sleep differs compared to women in other occupations, are needed to identify factors contributing to sleep disturbance in this population and inform interventions aimed at improving its sleep health.
Acknowledgements
We thank the women who participated in this study as well as the SAPPHIRE study team and community advisory board.
This work was supported by the National Institute on Drug Abuse (R01DA038499-01). During the study period, Laura Sisson was supported on a NIMH T32 training grant (T32MH122357; PI: Stuart). Darlynn M. Rojo-Wissar is supported by the National Institute of Mental Health’s Psychiatric Epidemiology Training Program (5T32MH014592-39; PI: Zandi, Peter). Dr. Spira received an honorarium from Springer Nature Switzerland AG for Guest Editing a Special Issue of Current Sleep Medicine Reports. Drs. Park and Sherman were supported in part by the Johns Hopkins University Center for AIDS Research (P30AI094189). The funders had no role in the study design, data collection, or in analysis and interpretation of the results, and this article does not necessarily reflect the views or opinions of the funders.
Footnotes
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