Heart rate and heart rate variability following sleep deprivation in retired night shift workers and retired day workers.

Shift workers experience poor sleep and dysregulated cardiac autonomic function during sleep. However, it is unknown if this dysregulation persists into retirement, potentially accelerating the age-associated risk for adverse cardiovascular outcomes. Using sleep deprivation as a physiological challenge to cardiovascular autonomic function, we compared heart rate (HR) and high-frequency heart rate variability (HF-HRV) during baseline and recovery sleep following sleep deprivation between retired night shift and day workers. Participants were retired night shift (N = 33) and day workers (N = 37) equated on age (mean [standard deviation] = 68.0 [5.6] years), sex (47% female), race/ethnicity (86% White), and body mass index. Participants completed a 60-h lab protocol including one night of baseline polysomnography-monitored sleep, followed by 36 h of sleep deprivation and one night of recovery sleep. Continuously recorded HR was used to calculate HF-HRV. Linear mixed models compared HR and HF-HRV during non-rapid eye movement (NREM) and REM sleep between groups during baseline and recovery nights. Groups did not differ on HR or HF-HRV during NREM or REM sleep (ps > .05) and did not show differential responses to sleep deprivation. In the full sample, HR increased and HF-HRV decreased from baseline to recovery during NREM (ps < .05) and REM (ps < .01). Both groups exhibited cardiovascular autonomic changes during recovery sleep following 36 h of sleep deprivation. Sleep deprivation appears to induce cardiovascular autonomic changes that persist into recovery sleep in older adults, regardless of shift work history.

Retired night shift workers exhibit poorer neurocognitive function compared to retired day workers.

STUDY OBJECTIVES: Shift work is associated with compromised cognitive function, and with chronic exposure, may place shift workers at elevated risk for dementia. However, evidence of cognitive impairment among former night shift workers is mixed, possibly due to inconsistencies regarding retirement status, work history classification, and cognitive assessments. To address these limitations, this study compared neurocognitive function between retired night shift workers and retired day workers using a well-characterized sample and a rigorous neurocognitive test battery. METHODS: Participants (N = 61; mean age: 67.9 ± 4.7 years; 61% females; 13% non-white) were 31 retired day workers and 30 retired night shift workers equated on age, sex, race/ethnicity, premorbid IQ, years retired, and diary-assessed habitual sleep characteristics. Participants completed a neurocognitive battery assessing six cognitive domains (language, visuospatial ability, attention, immediate and delayed memory, executive function) and self-reported cognitive function. Linear regression models compared groups on individual cognitive domains, adjusting for age, sex, race/ethnicity, education level, and habitual sleep quality. RESULTS: Retired night shift workers scored lower than retired day workers on attention (B = -0.38, 95% CI [-0.75, -0.02], p = .040) and executive function (B = -0.55, 95% CI [-0.92, -0.17], p = .005). In post hoc analyses, attention and executive function were unrelated to diary-assessed habitual sleep characteristics (disruption, timing, and irregularity) in retired night shift workers. CONCLUSIONS: The observed cognitive weaknesses in retired night shift workers may suggest increased risk for future dementia. Retired night shift workers should be followed to determine whether observed weaknesses progress.

Blood Pressure Cuff Inflation Briefly Increases Female Adolescents' Restlessness During Sleep on the First But Not Second Night of Ambulatory Blood Pressure Monitoring.

OBJECTIVE: Ambulatory blood pressure monitoring (ABPM) increases restlessness during adults' sleep in laboratory settings, but there is little evidence of an association among adolescents or in naturalistic environments. This study examined activity levels before and after blood pressure cuff inflation during sleep to determine whether and for how long ABPM increased restlessness during sleep in healthy adolescents. METHODS: Two hundred thirty-four healthy adolescents (mean age = 15.72 [1.30] years; 54% female; 57% Black) completed two consecutive nights of hourly ABPM and wrist-worn actigraphy. Activity counts during sleep, averaged across 5-minute bins, were compared in the 20 minutes before and after blood pressure cuff inflation using a four-level mixed model (bins within hours within nights within participants). Interactions of bin with night, sex, and race were examined. Covariates included age, sex, and race. RESULTS: Activity counts in the 5-minute bin immediately after cuff inflation were 10% to 14% higher than all other bins before ( p < .001) and after ( p < .001) cuff inflation. This effect differed by night and sex, as activity levels during 5-minute post-cuff inflation were elevated only on night 1 ( p values < .001) and only in female participants ( p values < .001). Effects did not differ by race. CONCLUSIONS: Cuff inflation during ABPM briefly increased adolescent female participants' restlessness during sleep. Habituation occurred after one night, so two nights of ABPM may minimize impact on sleep. If only one night of ABPM is feasible, excluding 5 minutes of actigraphy data after each cuff inflation may accommodate the impact of ABPM on restlessness during sleep.

Comparing polysomnography, actigraphy, and sleep diary in the home environment: The Study of Women's Health Across the Nation (SWAN) Sleep Study.

Study Objectives: Polysomnography (PSG) is considered the "gold standard" for assessing sleep, but cost and burden limit its use. Although wrist actigraphy and self-report diaries are feasible alternatives to PSG, few studies have compared all three modalities concurrently across multiple nights in the home to assess their relative validity across multiple sleep outcomes. This study compared sleep duration and continuity measured by PSG, actigraphy, and sleep diaries and examined moderation by race/ethnicity. Methods: Participants from the Study of Women's Health Across the Nation (SWAN) Sleep Study included 323 White (n = 147), African American (n = 120), and Chinese (n = 56) middle-aged community-dwelling women (mean age: 51 years, range: 48-57). PSG, wrist actigraphy (AW-64; Philips Respironics, McMurray, PA), and sleep diaries were collected concurrently in participants' homes over three consecutive nights. Multivariable repeated-measures linear models compared time in bed (TIB), total sleep time (TST), sleep efficiency (SE), sleep latency (SL), and wake after sleep onset (WASO) across modalities. Results: Actigraphy and PSG produced similar estimates of sleep duration and efficiency. Diaries yielded higher estimates of TIB, TST, and SE versus PSG and actigraphy, and lower estimates of SL and WASO versus PSG. Diary SL was shorter than PSG SL only among White women, and diary WASO was lower than PSG and actigraphy WASO among African American versus White women. Conclusions: Given concordance with PSG, actigraphy may be preferred as an alternative to PSG for measuring sleep in the home. Future research should consider racial/ethnic differences in diary-reported sleep continuity.

Influence of the menopausal transition on polysomnographic sleep characteristics: a longitudinal analysis.

STUDY OBJECTIVES: To evaluate how change in menopausal status related to spectral analysis and polysomnographic measures of sleep characteristics. METHODS: The Study of Women's Health Across the Nation (SWAN) Ancillary Sleep Study evaluated sleep characteristics of 159 women who were initially pre- or early perimenopausal and repeated the assessment about 3½ years later when 38 were pre- or early perimenopausal, 31 late perimenopausal, and 90 postmenopausal. Participants underwent in-home ambulatory polysomnography for two to three nights. Average EEG power in the delta and beta frequency bands was calculated during NREM and REM sleep, and sleep duration, wake after sleep onset (WASO), and apnea hypopnea index (AHI) were based on visually-scored sleep. RESULTS: The women who transitioned to postmenopause had increased beta NREM EEG power at the second assessment, compared to women who remained pre-or early premenopausal; no other sleep measures varied by change in menopausal status. In multivariate models the associations remained; statistical controls for self-reported hot flashes did not explain findings. In secondary analysis, NREM beta power at the second assessment was greater among women who transitioned into the postmenopause after adjustments for initial NREM beta power. CONCLUSIONS: Sleep duration and WASO did not vary by menopause transition group across assessments. Consistent with prior cross-sectional analysis, elevated beta EEG power in NREM sleep was apparent among women who transitioned to postmenopause, suggesting that independent of self-reported hot flashes, the menopausal transition is associated with physiological hyperarousal during sleep.

Meta-analysis of age and actigraphy-assessed sleep characteristics across the lifespan.

STUDY OBJECTIVES: Sleep quantity and continuity vary across the lifespan. Actigraphy is a reliable and widely used behavioral measure of sleep in research and personal health monitoring. This meta-analysis provides a novel examination of whether age (in years) is associated with actigraphy-assessed sleep across the lifespan. METHODS: A systematic search of PubMed, Embase.com, Cochrane CENTRAL, and PsycINFO using "actigraphy" and "sleep" terms provided 7079 titles/abstracts; studies of individuals with known psychiatric or medical comorbidities were excluded. Ninety-one articles (N = 23 365) provided data for six meta-analyses examining sleep duration (k = 89), sleep efficiency (k = 58), bedtime (k = 19) and waketime (k = 9) for individuals ages 6-21, and bedtime (k = 7) and waketime (k = 7) for individuals ages 22 and older. RESULTS: At older ages, sleep duration was shorter (r = -0.12) and sleep efficiency was lower (r = -0.05). Older age was associated with later bedtime (r = 0.37) and wake-up time (r = 0.24) from ages 6-21, whereas older age was associated with earlier bedtime (r = -0.66) and wake-up time (r = -0.59) for ages 22 and above. The strength of these associations was modified by study continent, but not by any other moderator. CONCLUSIONS: Age was negatively associated with actigraphy-assessed sleep duration and efficiency, but the effects were small in magnitude. On the other hand, large associations were observed between age and sleep timing, despite a smaller literature and the absence of analyzable data for ages 30-60. Changes in sleep timing, rather than changes in sleep duration or continuity, may better characterize the effects of age on human sleep.