Physical fatigue and its effect on road crossing decisions: an examination of the embodied perception perspective.

Road crossing is an everyday task that requires integration of information (e.g., speed and distance of an oncoming vehicle) to effectively guide behaviour. The embodied perception perspective suggests that individuals' perception of environmental stimuli is influenced by their psychophysiological state. Upon this premise, the current study examined whether acute physical fatigue influences visual perception and associated decision-making in road crossing. Using a between-subject design, 54 participants (healthy adults, aged 18-35) were divided into a fatigue and no-fatigue group. To manipulate fatigue, participants completed a vigorous cycling protocol (fatigue group) or a light cycling protocol (no-fatigue group) prior to completing a video-based examination of road crossing decisions (cross vs. not cross; action-based) and verbal judgments of speed and distance of an oncoming vehicle. Measures of heart rate, self-perceived recovery, and preferred walking speed indicated that fatigue was successfully induced (all p's < 0.03). Participants effectively distinguished between different speeds (30-50-70 km/h; p < 0.001), and distances (10-100 m in 10 m increments; p < 0.001). Moreover, both vehicle speed and distance (p's < 0.001) significantly influenced road crossing decisions. However, no significant effects of fatigue were observed for visual perception or road crossing decisions (all p's > 0.26). This study demonstrated that individuals are sensitive to changes in vehicle speed and distance and respond to these changes in making road crossing decisions. In contrast to the embodied perception perspective, however, physical fatigue did not alter perceptual judgments of vehicle speed and distance nor did it influence road crossing decisions in a video-simulated road crossing environment.

Comparison of Sleep Patterns in Vietnam Veterans With and Without Posttraumatic Stress Disorder Using Wrist Actigraphy.

STUDY OBJECTIVES: Disturbed sleep is a hallmark feature of posttraumatic stress disorder (PTSD). However, few studies have examined sleep objectively in individuals with PTSD compared to trauma-exposed controls. This study used wrist actigraphy to measure and compare sleep patterns in trauma-exposed Australian Vietnam veterans (VV) with and without PTSD. METHODS: Trauma-exposed Australian VV with and without PTSD were recruited from the PTSD Initiative. VV wore wrist accelerometers over 14 days and completed daily sleep diaries. Sleep parameters were compared between groups including sleep latency (SL), time in bed (TIB), total sleep time (TST), wake after sleep onset (WASO), and movement index (MI). Night-to-night and overall within-individual variability were assessed by root mean squared successive differences and comparison of individual standard deviations. Correlations between sleep diary (self-reported) and wrist actigraphy (objective) variables were also assessed. RESULTS: A total of 40 male VV (20 with PTSD) participated in the study. We found no difference in sleep patterns determined by wrist actigraphy between groups with the exception of reduced SL in VV with PTSD (3.9 ± 0.9 versus 4.9 ± 1.4 minutes, P < .05). Overall within-individual variability was significantly greater in VV with PTSD for TIB, TST, WASO, and MI. Self-reported and objective TST and WASO were more strongly correlated in VV without PTSD than those with PTSD. CONCLUSIONS: Although there were no significant differences in sleep parameters, VV with PTSD had increased within-individual overall sleep variability and reduced correlation between self-reported and objective sleep parameters compared to trauma-exposed controls. Further evaluation of extended sleep patterns by actigraphy in VV with PTSD is warranted.

Detailed Polysomnography in Australian Vietnam Veterans With and Without Posttraumatic Stress Disorder.

STUDY OBJECTIVES: Recent results from the PTSD Initiative, a cross-sectional cohort study in Australian Vietnam veterans (VV) with and without posttraumatic stress disorder (PTSD), demonstrated an increased prevalence of self-reported sleep disturbances in those with PTSD. This study aimed to objectively assess the prevalence of sleep disorders in the same cohort using detailed polysomnography (PSG). METHODS: Participants from the PTSD Initiative were recruited to undergo PSG. PTSD status was determined with the Clinician Administered PTSD Scale for DSM-5 (CAPS-5). Subjective sleep information was attained via structured questionnaires. Data from single night PSG were compared between trauma-exposed VV with and without PTSD. RESULTS: A total of 74 trauma-exposed male VV (40 with PTSD) underwent PSG (prospective n = 59, retrospective n = 15). All PSG parameters were similar between groups. No difference was seen in PSG-diagnosed obstructive sleep apnea (OSA) or periodic limb movements of sleep (PLMS). VV with PTSD showed a trend toward increased duration of sleep with oxygen saturations < 90% (10% versus 1.8%; P = .07). VV with PTSD reported increased sleep onset latency (42.4 versus 13.3 minutes; P < .01); were less likely to report sleeping well (32.5% versus 67.5%; P < .01); had higher OSA risk using Berlin Questionnaire (BQ) (70% versus 38.2%; P < .01); and had higher rates of partner-reported limb movements (56.4% versus 17.6%; P < .01). No association between PSG-diagnosed OSA and PTSD severity was evident. CONCLUSIONS: In Australian VV with and without PTSD, no difference was seen across all PSG parameters including the diagnosis and severity of OSA and PLMS. However, VV with PTSD demonstrated an increased perception of sleep disturbances.

Sleep Disturbances in Australian Vietnam Veterans With and Without Posttraumatic Stress Disorder.

STUDY OBJECTIVES: Posttraumatic stress disorder (PTSD) is a condition that may develop after a traumatic event, particularly combat-related trauma. Although sleep disturbance is a hallmark of PTSD, the prevalence of sleep disturbances in Australian veterans with PTSD remains uncertain. This study aimed to subjectively compare the prevalence of sleep disturbances in Australian Vietnam veterans with and without PTSD. METHODS: A cross-sectional cohort study compared trauma-exposed Australian Vietnam veterans with and without PTSD. PTSD diagnosis was confirmed using the Clinician Administered PTSD Scale for DSM-5. Sleep information was evaluated using supervised structured questionnaires, including Epworth Sleepiness Scale (ESS) and Berlin and Mayo Questionnaires. RESULTS: Two hundred fourteen male Vietnam veterans (108 with PTSD) were included. Participants with PTSD had higher body mass index (30.3 versus 29 kg/m2; P < .05), higher ESS score (9.2 versus 7.6; P < .05), and increased alcohol or medication use to assist with sleep (19% versus 6%; P < .01; and 44% versus 14%; P < .01). Those with PTSD were less likely to sleep well (32% versus 72%; P < .01) and reported higher rates of restless legs (45% versus 25%; P < .01), nightmares (91% versus 29%; P < .01), nocturnal screaming (73% versus 18%; P < .01), sleep terrors (61% versus 13%; P < .01) and dream enactment (78% versus 11.8%; P < .01). The PTSD group had higher rates of diagnosed OSA (42% versus 21%; P < .01) and an increased risk of OSA on the Berlin Questionnaire (69% versus 43%; P < .01). CONCLUSIONS: Compared to trauma-exposed controls, Australian Vietnam veterans with PTSD demonstrated an increased prevalence of a wide range of sleep disturbances, including OSA. In veterans with PTSD, detailed sleep assessment, including consideration of polysomnography, is paramount.

Physical comorbidities of post-traumatic stress disorder in Australian Vietnam War veterans.

OBJECTIVE: To determine whether the prevalence of physical comorbidities in Australian Vietnam War veterans with post-traumatic stress disorder (PTSD) is higher than in trauma-exposed veterans without PTSD. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional analysis of the health status (based on self-reported and objective clinical assessments) of 298 Australian Vietnam War veterans enrolled by the Gallipoli Medical Research Institute (Brisbane) during February 2014 - July 2015, of whom 108 were confirmed as having had PTSD and 106 served as trauma-exposed control participants.Main outcomes and measures: Diagnostic psychiatric interview and psychological assessments determined PTSD status, trauma exposure, and comorbid psychological symptoms. Demographic data, and medical and sleep history were collected; comprehensive clinical examination, electrocardiography, spirometry, liver transient elastography, and selected pathology assessments and diagnostic imaging were performed. Outcomes associated with PTSD were identified; regression analysis excluded the effects of potentially confounding demographic and risk factors and comorbid symptoms of depression and anxiety. RESULTS: The mean total number of comorbidities was higher among those with PTSD (17.7; SD, 6.1) than in trauma-exposed controls (14.1; SD, 5.2; P < 0.001). For 24 of 171 assessed clinical outcomes, morbidity was greater in the PTSD group, including for conditions of the gastrointestinal, hepatic, cardiovascular, and respiratory systems, sleep disorders, and laboratory pathology measures. In regression analyses including demographic factors, PTSD remained positively associated with 17 adverse outcomes; after adjusting for the severity of depressive symptoms, it remained significantly associated with ten. CONCLUSION: PTSD in Australian Vietnam veterans is associated with comorbidities in several organ systems, independent of trauma exposure. A comprehensive approach to the health care of veterans with PTSD is needed.