Emotional response to perceived racism and nocturnal heart rate variability in young adult African Americans.

BACKGROUND: Heightened autonomic nervous system (ANS) arousal is a well-established contributor to the effect of stress on adverse cardiovascular health outcomes which disproportionately affect African Americans. ANS arousal is normally attenuated during sleep and compromise of this shift is associated with multiple adverse cardiovascular outcomes. Parasympathetic nervous system (PNS) dominance during sleep can be altered by stress. Racism has been recognized to have many negative health consequences in African Americans. Perceived racism has been linked to ANS activity, however, we are not aware of prior research on racism and nocturnal ANS balance. OBJECTIVE: To examine relationships between perceived racism and nocturnal ANS activity indexed by heart rate variability (HRV) in healthy African American men and women age 18-35. METHODS: Fifty-four participants completed the Perceived Racism Scale and had 24-hour ambulatory electrocardiogram recordings in their homes. Power spectral analysis was used to derive normalized high frequency (nHF) to index PNS activity which was computed by 5-minute epochs during wake and sleep. RESULTS: Endorsement of racism and negative emotional reactions during the past year were inversely related to nHF during time in bed. Multiple regression analysis indicated that negative emotional reactions were a significant predictor of nHF during the sleep period F(2,54) = 4.213, p = .020, R2 = 0.135 (adjusted R2 = 0.103). Relationships during wake were not statistically significant. CONCLUSION: Findings suggest that perseverative thoughts triggered by negative emotional reactions to racism influencing nocturnal ANS activity may be a pathway by which perceived racism affects health. Support: 3UL1TR001409-02S1 and R01HL087995 to Dr. Mellman.

Period 3 gene polymorphism and sleep adaptation to stressful urban environments.

This study's objective was to investigate the relationship between a variable-number tandem-repeat (VNTR) Period 3 gene (PER3) polymorphism and sleep adaptation to stressful urban environments. Seventy-five (49 female) African American participants (ages 18-35 years) living in neighbourhoods with high rates of violent crime were selected for the study based on converging criteria for good or poor sleep. Categorization of sleep quality was based on the Insomnia Severity Index (ISI), estimates of typical sleep duration and sleep efficiency. Other assessments included the Fear of Sleep Index (FOSI) and City Stress Inventory (CSI). Whole blood DNA was analysed for the 4 and 5 VNTR alleles using polymerase chain reaction (PCR) and restrictive enzyme digestion. Fifty-seven per cent of those who were homo- or heterozygous for the 4-repeat allele were poor sleepers versus 25% of those homozygous for the 5-repeat allele; χ2  = 4.17, P = 0.041. In a logistic regression model with all the variables with significant bivariate relationships to sleep quality group, FOSI was the only significant predictor (χ2  = 5.68, P = 0.017). FOSI scores were higher among those with the 4-repeat allele (t = 2.66, P = 0.013). The PER3 4 and 5 VNTR polymorphisms appear to influence sensitivity to the effects of stressful urban environments on sleep. While FOSI was the only variable associated independently with sleep quality category, the candidate vulnerability allele was also associated with greater 'fear of sleep'.

Sleep and Processing of Trauma Memories.

Sleep has been implicated in learning processes that appear to underlie recovery from posttraumatic stress disorder (PTSD). The importance of quality and timing of sleep following exposure-based therapies has been suggested. The present study evaluated relationships between sleep and adaptive emotional processing following written narrative exposure (WNE) to memories of traumatic events experienced by participants with clinically significant PTSD symptoms. Participants included 21 urban-residing nontreatment-seeking adults with full or subthreshold symptoms of PTSD who completed 4 sessions of 30-min WNE with the first session either in the evening or the morning. There was a significant reduction of PTSD symptom severity after WNE sessions (partial η = .65), but there was no interaction between group assignment based on the initial session's proximity to sleep and initial reduction of PTSD symptom severity (partial η = .01). Polysomnography following evening WNE revealed increased duration of total sleep and N2%, reduced N3%, and increased eye movement density during REM sleep compared with baseline recordings (dz = 0.65 to 1.15). Reduced N3% and increased REM density were associated with less improvement of PTSD symptoms (r = .58 & -.63). These findings suggest a relationship between preservation of diminished arousal during sleep and adaptive trauma memory processing.

The impact of posttraumatic stress disorder versus resilience on nocturnal autonomic nervous system activity as functions of sleep stage and time of sleep.

Posttraumatic stress disorder (PTSD) has been associated with sleep disturbances including alterations in sleep stages and recently, elevated nocturnal autonomic nervous system (ANS) arousal (i.e., dominance of the sympathetic nervous system over the parasympathetic nervous system). Data suggest that sleep contributes to the regulation of ANS activity. In our previous ambulatory heart rate variability (HRV) monitoring study, strong relationships between sleep and nocturnal ANS activity in resilient participants (i.e., individuals who had never had PTSD despite exposure to high-impact trauma) were not seen with PTSD. In this study, we examined the impact of PTSD vs. resilience on ANS activity as a function of sleep stage and time of sleep. Participants (age 18-35) with current PTSD (n=38) and resilience (n=33) completed two overnight polysomnography recordings in a lab setting. The second night electrocardiogram was analyzed for frequency domain HRV parameters and heart rate within rapid-eye-movement (REM) and non-REM (NREM) sleep periods. Results indicated that ANS arousal indexed by HRV was greater during REM compared with NREM sleep and that the REM-NREM difference was greater in the PTSD than in the resilient participants. This effect of PTSD was reduced to non-significance when analyses controlled for REM sleep percentage, which was lower with PTSD. Exploratory analyses revealed that the REM-NREM difference in HRV was correlated with REM sleep percentage in resilient participants, but not with PTSD. In contrast with our data from home settings, the present study did not find increased overall nocturnal ANS arousal with PTSD. Analyses did reveal higher heart rate during initial NREM sleep with more rapid decline over the course of NREM sleep with PTSD compared with resilience. Findings suggest that elevated ANS arousal indexed by heart rate with PTSD is specific to the early part of sleep and possible impairment in regulating ANS activity with PTSD related to REM sleep.

Blood Pressure Dipping and Urban Stressors in Young Adult African Americans.

BACKGROUND: Blunted nocturnal blood pressure (BP) dipping is an early marker of cardiovascular risk that is prevalent among African Americans. PURPOSE: We evaluated relationships of BP dipping to neighborhood and posttraumatic stress and sleep in urban residing young adult African Americans. METHODS: One hundred thirty-six black, predominately African American, men and women with a mean age of 22.9 years (SD = 4.6) filled out surveys and were interviewed and had two, 24-h ambulatory BP recordings. RESULTS: Thirty-eight percent had BP dipping ratios < .10. Wake after sleep onset (WASO), neighborhood disorder and neighborhood poverty rates but not posttraumatic stress symptoms, and other sleep measures correlated significantly with dipping ratios. Models with the neighborhood measures that also included WASO increased the explained variance. CONCLUSIONS: Studies elucidating mechanisms underlying effects of neighborhoods on BP dipping and the role of disrupted sleep, and how they can be mitigated are important directions for future research.

Nocturnal autonomic balance and sleep in PTSD and resilience.

Posttraumatic stress disorder (PTSD) has been associated with heightened nocturnal autonomic nervous system (ANS) arousal and sleep disturbances. It has been suggested that relationships between sleep and nocturnal ANS activity are influenced by insomnia; however, investigation of this relationship has been limited in PTSD. This study examined nocturnal ANS activity and its relationship to sleep in PTSD and resilience. Physically healthy young adult African Americans with current PTSD (n = 20) or who had never had PTSD despite exposure to a high-impact traumatic event (resilient, n = 18) were monitored with ambulatory electrocardiograms and actigraphy for 24-hr periods. Frequency-domain heart-rate variability measures, that is, low-frequency to high-frequency ratios (LF/HF), which index sympathetic nervous system activity, and normalized HF (nHF), which indexes parasympathetic nervous system activity were examined. Normalized HF during the time-in-bed period was lower for those with PTSD than those with resilience (p = .041). Total sleep time was strongly correlated with time-in-bed LF/HF (r = -.72) and nHF (r = .75) in the resilient group, but these were not correlated in the PTSD group. The results suggest elevated nocturnal ANS arousal and dissociation between ANS activity and total sleep time in PTSD.

A relationship between REM sleep measures and the duration of posttraumatic stress disorder in a young adult urban minority population.

STUDY OBJECTIVE: To determine relationships of polysomnographic (PSG) measures with posttraumatic stress disorder (PTSD) in a young adult, urban African American population. DESIGN: Cross-sectional, clinical and laboratory evaluation. SETTING: Community recruitment, evaluation in the clinical research unit of an urban University hospital. PARTICIPANTS: Participants (n = 145) were Black, 59.3% female, with a mean age of 23.1 y (SD = 4.8). One hundred twenty-one participants (83.4%) met criteria for trauma exposure, the most common being nonsexual violence. Thirty-nine participants (26.9%) met full (n = 19) or subthreshold criteria (n = 20) for current PTSD, 41 (28.3%) had met lifetime PTSD criteria and were recovered, and 65 (45%) were negative for PTSD. MEASUREMENTS AND RESULTS: Evaluations included the Clinician Administered PTSD Scale (CAPS) and 2 consecutive nights of overnight PSG. Analysis of variance did not reveal differences in measures of sleep duration and maintenance, percentage of sleep stages, and the latency to and duration of uninterrupted segments of rapid eye movement (REM) sleep by study group. There were significant relationships between the duration of PTSD and REM sleep percentage (r = 0.53, P = 0.001), REM segment length (r = 0.43, P = 0.006), and REM sleep latency (r = -0.34, P < 0.03) among those with current PTSD that persisted when removing cases with, or controlling for, depression. CONCLUSIONS: The findings are consistent with observations in the literature of fragmented and reduced REM sleep with posttraumatic stress disorder (PTSD) relatively proximate to trauma exposure and nondisrupted or increased REM sleep with chronic PTSD. CITATION: Mellman TA, Kobayashi I, Lavela J, Wilson B, Hall Brown TS. A relationship between REM sleep measures and the duration of posttraumatic stress disorder in a young adult urban minority population.

Subjectively and objectively measured sleep with and without posttraumatic stress disorder and trauma exposure.

STUDY OBJECTIVES: Although reports of sleep disturbances are common among individuals with posttraumatic stress disorder (PTSD), results of polysomnographic (PSG) studies have inconsistently documented abnormalities and have therefore suggested "sleep state misperception." The authors' study objectives were to compare sleep parameters measured objectively and subjectively in the laboratory and at home in civilians with and without trauma exposure and PTSD. DESIGN: Cross-sectional study. SETTING: PSG recordings in a sleep laboratory and actigraphic recordings in participants' homes. PARTICIPANTS: One hundred three urban-residing African Americans with and without trauma exposure and PTSD who participated in a larger study. INTERVENTIONS: N/A. MEASUREMENTS: Sleep parameters (total sleep time [TST], sleep onset latency [SOL], and wake after sleep onset [WASO]) were assessed using laboratory PSG and home actigraphy. A sleep diary was completed in the morning after PSG and actigraphy recordings. Habitual TST, SOL, and WASO were assessed using a sleep questionnaire. The Clinician Administered PTSD Scale was administered to assess participants' trauma exposure and PTSD diagnostic status. RESULTS: Participants, regardless of their trauma exposure/PTSD status, underestimated WASO in the diary and questionnaire relative to actigraphy and overestimated SOL in the diary relative to PSG. Among participants with current PTSD, TST diary estimates did not differ from the actigraphy measure in contrast with those without current PTSD who overestimated TST. No other significant group differences in discrepancies between subjective and objective sleep measures were found. CONCLUSIONS: Discrepancies between subjectively and objectively measured sleep parameters were not associated with trauma exposure or PTSD. This challenges prior assertions that individuals with PTSD overreport their sleep disturbances.