Publications

STUDY OBJECTIVES: We compared resident physician work hours and sleep in a multicenter clustered-randomized crossover clinical trial that randomized resident physicians to an Extended Duration Work Roster (EDWR) with extended-duration (≥24 hr) shifts or a Rapidly Cycling Work Roster (RCWR), in which scheduled shift lengths were limited to 16 or fewer consecutive hours.

METHODS: Three hundred two resident physicians were enrolled and completed 370 1 month pediatric intensive care unit rotations in six US academic medical centers. Sleep was objectively estimated with wrist-worn actigraphs. Work hours and subjective sleep data were collected via daily electronic diary.

RESULTS: Resident physicians worked fewer total hours per week during the RCWR compared with the EDWR (61.9 ± 4.8 versus 68.4 ± 7.4, respectively; p < 0.0001). During the RCWR, 73% of work hours occurred within shifts of ≤16 consecutive hours. In contrast, during the EDWR, 38% of work hours occurred on shifts of ≤16 consecutive hours. Resident physicians obtained significantly more sleep per week on the RCWR (52.9 ± 6.0 hr) compared with the EDWR (49.1 ± 5.8 hr, p < 0.0001). The percentage of 24 hr intervals with less than 4 hr of actigraphically measured sleep was 9% on the RCWR and 25% on the EDWR (p < 0.0001).

CONCLUSIONS: RCWRs were effective in reducing weekly work hours and the occurrence of >16 consecutive hour shifts, and improving sleep duration of resident physicians. Although inclusion of the six operational healthcare sites increases the generalizability of these findings, there was heterogeneity in schedule implementation. Additional research is needed to optimize scheduling practices allowing for sufficient sleep prior to all work shifts.Clinical Trial: Multicenter Clinical Trial of Limiting Resident Work Hours on ICU Patient Safety (ROSTERS), https://clinicaltrials.gov/ct2/show/NCT02134847.

OBJECTIVE: Women's sleep at menopause is widely reported to be problematic. The Insomnia Severity Index (ISI) is a commonly used tool for quantifying sleep problems in clinical and research settings, but psychometric properties in postmenopausal women have not been reported. Our study aim was to examine the factor structure of the ISI in a large and diverse sample of midlife women with hot flashes.

METHODS: Baseline data were from 899 women enrolled in one of the three clinical trials using similar entry criteria conducted by the Menopause Strategies Finding Lasting Answers to Symptoms and Health research network. We conducted confirmatory factor analyses for the total sample and within strata defined by race/ethnicity (black and white women).

RESULTS: The ISI had two factors in the total sample. The two-factor structure was consistent across black and white women, with the exception of one item "difficulty falling asleep."

CONCLUSIONS: The ISI in midlife women with hot flashes is composed of two factors that capture dimensions of the insomnia severity and daytime impact. The instrument is a psychometrically sound scale appropriate for use in research and clinical practice to capture the severity and daytime impact of insomnia symptoms in diverse samples of midlife women with hot flashes. An abbreviated screening of two items could be considered to determine if further evaluation is needed of sleep complaints.

OBJECTIVES: Given the neurocognitive hyperarousal observed in patients with insomnia disorder and associations of nocturnal hot flashes with cardiovascular disease risk, we examined whether women with hot flash-associated insomnia disorder demonstrate exaggerated cardiovascular responsivity to acute stressors, and also a profile of psychological hyperarousal.

METHODS: Peri and postmenopausal women with and without hot flash-associated insomnia disorder underwent assessments of cardiovascular autonomic responsivity to acute stress paradigms and psychological hyperarousal. Hemodynamic responses (heart rate, blood pressure) to nociceptive, social-evaluative, and cognitive stress paradigms were measured in the morning. Psychological hyperarousal was evaluated using questionnaires assessing daytime and presleep hyperarousal, anxiety, and sleep-related cognitions.

RESULTS: Women (25 with and 15 without hot flash-associated insomnia) aged 53.4 ± 4.8 years reported a range of insomnia symptoms. Resting-state hemodynamics were similar between groups. Heart rate and blood pressure responses to stress paradigms did not differ by group nor did they correlate with insomnia severity. Women with insomnia disorder had higher generalized anxiety disorder scores (mean 2.7 ± 3.0 vs 1.0 ± 1.4; P = 0.05) and sleep-related cognitions than those without insomnia (P ≤ 0.05). Insomnia symptom severity was moderately correlated with presleep and daytime hyperarousal, anxiety, and sleep-related cognition (all r ≥ 0.43).

CONCLUSIONS: Though hot flash-associated insomnia is characterized by psychological hyperarousal before sleep and during the daytime, it does not relate to cardiovascular responsiveness to acute stressors. Our findings do not support the hypothesis that altered cardiovascular control is a potential mechanism by which hot flash-associated insomnia confers higher cardiovascular disease risk.

INTRODUCTION: While the Accreditation Council for Graduate Medical Education limited first year resident-physicians to 16 consecutive work hours from 2011 to 2017, resident-physicians in their second year or higher were permitted to work up to 28 h consecutively. This paper describes the Randomized Order Safety Trial Evaluating Resident-physician Schedules (ROSTERS) study, a clustered-randomized crossover clinical trial designed to evaluate the effectiveness of eliminating traditional shifts of 24 h or longer for second year or higher resident-physicians in pediatric intensive care units (PICUs).

METHODS: ROSTERS was a multi-center non-blinded trial in 6 PICUs at US academic medical centers. The primary aim was to compare patient safety between the extended duration work roster (EDWR), which included shifts ≥24 h, and a rapidly cycling work roster (RCWR), where shifts were limited to a maximum of 16 h. Information on potential medical errors was gathered and used for classification by centrally trained physician reviewers who were blinded to the study arm. Secondary aims were to assess the relationship of the study arm to resident-physician sleep duration, work hours and neurobehavioral performance.

RESULTS: The study involved 6577 patients with a total of 38,821 patient days (n = 18,749 EDWR, n = 20,072 RCWR). There were 413 resident-physician rotations included in the study (n = 203 EDWR, n = 210 RCWR). Resident-physician questionnaire data were over 95% complete.

CONCLUSIONS: Results from data collected in the ROSTERS study will be evaluated for the impact of resident-physician schedule roster on patient safety outcomes in PICUs, and will allow for examination of a number of secondary outcome measures. ClinicalTrials.gov Identifier: NCT02134847.

Light is the most effective environmental stimulus for shifting the mammalian circadian pacemaker. Numerous studies have been conducted across multiple species to delineate wavelength, intensity, duration, and timing contributions to the response of the circadian pacemaker to light. Recent studies have revealed a surprising sensitivity of the human circadian pacemaker to short pulses of light. Such responses have challenged photon counting-based theories of the temporal dynamics of the mammalian circadian system to both short- and long-duration light stimuli. Here, we collate published light exposure data from multiple species, including gerbil, hamster, mouse, and human, to investigate these temporal dynamics and explore how the circadian system integrates light information at both short- and long-duration time scales to produce phase shifts. Based on our investigation of these data sets, we propose 3 new interpretations: (1) intensity and duration are independent factors of total phase shift magnitude, (2) the possibility of a linear/log temporal function of light duration that is universal for all intensities for durations less than approximately 12 min, and (3) a potential universal minimum light duration of  0.7 sec that describes a "dead zone" of light stimulus. We show that these properties appear to be consistent across mammalian species. These interpretations, if confirmed by further experiments, have important practical implications in terms of understanding the underlying physiology and for the design of lighting regimens to reset the mammalian circadian pacemaker.

Visible light is the principal stimulus for resetting the mammalian central circadian pacemaker. Circadian phase resetting is most sensitive to short-wavelength (blue) visible light. We examined the effects of removing short-wavelengths < 500 nm from polychromatic white light using optical filters on circadian phase resetting in rats. Under high irradiance conditions, both long- (7 h) and short- (1 h) duration short-wavelength filtered (< 500 nm) light exposure attenuated phase-delay shifts in locomotor activity rhythms by (∼40-50%) as compared to unfiltered light exposure. However, there was no attenuation in phase resetting under low irradiance conditions. Additionally, the reduction in phase-delay shifts corresponded to regionally specific attenuation in molecular markers of pacemaker activation in response to light exposure, including c-FOS, Per1 and Per2. These results demonstrate that removing short-wavelengths from polychromatic white light can attenuate circadian phase resetting in an irradiance dependent manner. These results have important implications for designing and optimizing lighting interventions to enhance circadian adaptation.

The effects of soccer-related head impacts, beyond overt concussions, on Patient Reported Outcomes (PROs) have not been explored to date. Generalized estimating equations were employed to determine the association between soccer-related head impacts (headers in the prior 2 weeks, unintentional head impacts in the prior 2 weeks, headers in the prior 12 months and lifetime concussions) on PROs including depression, anxiety, sleep disturbance and sleep impairment. Compared to players with no unintentional head impacts in the prior 2 weeks, players with one unintentional exposure reported more symptoms of anxiety (p = 0.002) and players with 2+ exposures reported more symptoms of depression (p = 0.006) and anxiety (p < 0.001). In contrast, players in the 3rd Quartile of 12 mo. headers reported less anxiety (p = 0.001), sleep disturbance (p = 0.002) and sleep impairment (p < 0.001) compared to those in the 1st quartile. Unintentional head impacts are associated with worse PROs while more headers are paradoxically associated with better PROs.

Purpose To examine the role of sex in abnormal white matter microstructure after soccer heading as identified by using the diffusion-tensor imaging (DTI) metric fractional anisotropy (FA). Materials and Methods In this prospective cross-sectional study, 98 individuals who were enrolled in a larger prospective study of amateur soccer players (from 2013 to 2016) were matched 1:1 for age and history of soccer heading in the prior 12 months. Among the subjects, 49 men (mean age, 25.7 years; range, 18-50 years) and 49 women (mean age, 25.8 years; range, 18-50 years) with median total soccer headings per year of 487 and 469, respectively, underwent 3.0-T DTI. Images were registered to the Johns Hopkins University template. A voxelwise linear regression was fitted for FA with terms for the number of headings during the previous 12 months and its interaction with sex after controlling for the following potential confounders: age, years of education, number of lifetime concussions, and handedness. In the resulting statistical maps, P < .01 indicated a statistically significant difference, with a threshold cluster size larger than 100 mm3. Results Among men, three regions were identified in which greater heading exposure was associated with lower FA; eight such regions were identified among women (>100 contiguous voxels, P < .01). In seven of the eight regions identified in women, the association between heading and FA was stronger in women than in men. There was no significant difference of heading with FA between the sexes for any region in which heading was associated with FA among men (P > .01, <100 contiguous voxels). Conclusion With similar exposure to heading, women exhibit more widespread evidence of microstructural white matter alteration than do men, suggesting preliminary support for a biologic divergence of brain response to repetitive trauma. © RSNA, 2018 Online supplemental material is available for this article.

STUDY OBJECTIVES: The Menopause Strategies: Finding Lasting Answers for Symptoms and Health network conducted three randomized clinical trials (RCTs) testing six interventions treating vasomotor symptoms (VMS), and also collected self-reported sleep outcomes. A fourth RCT assessed an intervention for insomnia symptoms among women with VMS. We describe these seven interventions' effects relative to control in women with comparably severe insomnia symptoms and VMS.

METHODS: We analyzed pooled individual-level data from 546 peri- and postmenopausal women with Insomnia Severity Index (ISI) ≥ 12, and ≥14 bothersome VMS/week across the four RCTs. Interventions included the following: escitalopram 10-20 mg/day; yoga; aerobic exercise; 1.8 g/day omega-3 fatty acids; oral 17-beta-estradiol 0.5-mg/day; venlafaxine XR 75-mg/day; and cognitive behavioral therapy for insomnia (CBT-I). Outcome measures were ISI and Pittsburgh Sleep Quality Index (PSQI) over 8-12 weeks of treatment.

RESULTS: CBT-I produced the greatest reduction in ISI from baseline relative to control at -5.2 points (95% CI -7.0 to -3.4). Effects on ISI were similar for exercise at -2.1 and venlafaxine at -2.3 points. Comparably small decreases in ISI were observed with escitalopram, yoga, and estradiol. The largest reduction in PSQI from baseline was with CBT-I at -2.7 points (-3.9 to -1.5), although PSQI decreases of 1.2 to 1.6 points were significantly better than control with escitalopram, exercise, yoga, estradiol, and venlafaxine. Omega-3 supplements did not improve insomnia symptoms.

CONCLUSIONS: This study's findings support current recommendations for CBT-I as a first line treatment in healthy midlife women with insomnia symptoms and moderately bothersome VMS.

Accumulating evidence points to a genetic contribution to explain inter-individual vulnerability to sleep deprivation. A functional polymorphism in the BDNF gene, which causes a valine (Val) to methionine (Met) amino acid substitution at Codon 66, has been associated with cognitive impairment, particularly in populations with impaired frontal functioning. We hypothesised that sleep deprivation, which affects frontal function, may lead to cognitive dysfunction in Met allele carriers. To examine this, we investigated, in different BDNF genotypes, the effects of sleep deprivation on cognitive flexibility, as measured by response inhibition using the Stroop Color Naming Task. Thirty healthy, adults of European ancestry, including 12 heterozygous Met allele carriers and 18 Val/Val homozygotes, underwent 30-h of extended wakefulness under constant routine conditions. A computerised Stroop task was administered every 2h. Error rate and reaction times increased with time awake for all individuals. Participants with the Val/Met genotype made more errors on incongruent trials after 20h awake. While Val/Met participants also took significantly longer to respond when inhibiting a prepotent response irrespective of time awake, this was particularly evident during the biological night. Our study shows that carriers of the BDNF Met allele are more vulnerable to the impact of prolonged wakefulness and the biological night on a critical component of executive function, as measured by response inhibition on the Stroop task.