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1.  Sleeping under the Ocean: Despite Total Isolation, Nuclear Submariners Maintain Their Sleep and Wake Patterns throughout Their Under Sea Mission 
PLoS ONE  2015;10(5):e0126721.
Background
To assess the effects of isolation, inadequate exposure to light and specific shift work on the subjective and objective measurements of sleep and alertness of submariners.
Purpose
A strictly controlled randomized crossover study with the polysomnography recorded twice during the mission.
Methods
Setting: Shift and night work with prolonged (70 days) social isolation from the real world (with no phone or Internet contact with families or friends during a routine mission aboard the “Téméraire” French Strategic Submarine with Ballistic Nuclear missiles (SSBN). Participants: 19 submariners working on a 24-hour shift for three days in a row schedule. Interventions: The participants attended two polysomnographic (PSG) recordings of night sleep on Day 21 (D21) and Day 51 (D51) of the 70-day patrol; urine cortisol levels were also taken after sleep, and subjective assessments of sleep, sleepiness, mood and anxiety on D21 and D51. The light and temperature on board were also recorded.
Results
PSG analyses showed that sleep did not significantly vary in length (total sleep time) or in quality between D21 and D51. The mariners reported the same subjective sleep, sleepiness, anxiety or mood (except for a slightly worse score for confusion on D51). Blood cortisol levels did not vary significantly.
Conclusions
These results show that humans living in an isolated environment for more than two months with this specific shift schedule do not suffer from any significant effects on sleep, sleepiness and confusion between D21 and D51, when they follow an organized regular shift pattern with controlled light and temperature.
doi:10.1371/journal.pone.0126721
PMCID: PMC4446350  PMID: 26016656
2.  Urinary Interleukin-8 Is a Biomarker of Stress in Emergency Physicians, Especially with Advancing Age — The JOBSTRESS* Randomized Trial 
PLoS ONE  2013;8(8):e71658.
Background
Emergency physicians are exposed to greater stress during a 24-hour shift (24 hS) than a 14-hour night shift (14 hS), with an impact lasting several days. Interleukin-8 (IL-8) is postulated to be a chronic stress biomarker. However, no studies have tracked IL-8 over several shifts or used it for monitoring short-term residual stress. The IL-8 response to the shifts may also increase with age. Conveniently, IL-8 can be measured non-intrusively from urine.
Methods
We conducted a shifts-randomized trial comparing 17 emergency physicians’ urinary IL-8 levels during a 24 hS, a 14 hS, and a control day (clerical work on return from leave). Mean levels of IL-8 were compared using a Wilcoxon matched-pairs test. Independent associations of key factors including shifts, stress, and age with IL-8 levels were further assessed in a multivariable generalized estimating equations model.
Results
Mean urinary IL-8 levels almost doubled during and after a 24 hS compared with a 14 hS or a control day. Furthermore, IL-8 levels failed to return to control values at the end of the third day after the shift despite a rest day following the 24 hS. In the multivariable model, engaging in a 24 hS, self-reported stress, and age were independently associated with higher IL-8 levels. A 24 hS significantly increased IL-8 levels by 1.9 ng (p = .007). Similarly, for every unit increase in self-reported stress, there was a 0.11 ng increase in IL-8 levels (p = .003); and for every one year advance in age of physicians, IL-8 levels also increased by 0.11 ng (p = .018).
Conclusion
The 24 hS generated a prolonged response of the immune system. Urinary IL-8 was a strong biomarker of stress under intensive and prolonged demands, both acutely and over time. Because elevated IL-8 levels are associated with cardiovascular disease and negative psychological consequences, we suggest that emergency physicians limit their exposure to 24 hS, especially with advancing age.
doi:10.1371/journal.pone.0071658
PMCID: PMC3747272  PMID: 23977105
3.  The long-term effects of occupational exposure to vinyl chloride monomer on microcirculation: a cross-sectional study 15 years after retirement 
BMJ Open  2013;3(6):e002785.
Objectives
To assess residual long-term microcirculation abnormalities by capillaroscopy, 15 years after retiring from occupational exposure to vinyl chloride monomer (VCM).
Design
Cross-sectional study.
Setting
Allier, one of the major areas of polyvinyl chloride production in France.
Participants
We screened 761 (97% men) retired workers exposed to chemical toxics. Exposure to chemicals other than VCM excluded potential participants.
Primary and secondary outcome measures
These participants underwent a medical examination including a capillaroscopy, symptoms of Raynaud and comorbidities, as well as a survey to determine exposure time, direct or indirect contact, type of occupation, smoking status and time after exposure. A double blind analysis of capillaroscopic images was carried out. A control group was matched in age, sex, type of occupation.
Results
179/761 retired workers were only exposed to VCM at their work, with 21 meeting the inclusion criteria and included. Exposure time was 29.8±1.9 years and time after exposure was 15.9±2.4 years. Retired workers previously exposed to VCM had significantly higher capillaroscopic modifications than the 35 controls: enlarged capillaries (19% vs 0%, p<0.001), dystrophy (28.6% vs 0%, p=0.0012) and augmented length (33% vs 0%, p<0.001). Time exposure was linked (p<0.001) with enlarged capillaries (R2=0.63), dystrophy (R2=0.51) and capillary length (R2=0.36). They also had higher symptoms of Raynaud (19% vs 0%, p=0.007) without correlation with capillaroscopic modifications.
Conclusions
Although VCM exposure was already known to affect microcirculation, our study demonstrates residual long-term abnormalities following an average of 15 years’ retirement, with a time-related exposure response. Symptoms of Raynaud, although statistically associated with exposure, were not related to capillaroscopic modifications; its origin remains to be determined.
doi:10.1136/bmjopen-2013-002785
PMCID: PMC3686170  PMID: 23794583
Occupational & Industrial Medicine; Chemical Pathology; Public Health
4.  Conscious Presence and Self Control as a measure of situational awareness in soldiers – A validation study 
Background
The concept of `mindfulness´ was operationalized primarily for patients with chronic stressors, while it is rarely used in reference to soldiers. We intended to validate a modified instrument on the basis of the Freiburg Mindfulness Inventory (FMI) to measure soldiers’ situational awareness (“mindfulness”) in stressful situations/missions. The instrument we will explore in this paper is termed the Conscious Presence and Self Control (CPSC) scale.
Methods
The CPSC and further instruments, i.e., Perceived Stress Scale (PSS), stressful military experiences (PCL-M), life satisfaction (BMLSS), Positive Life Construction (ePLC), and self-perceived health affections (VAS), were administered to 281 German soldiers. The soldiers were mainly exposed to explosive ordnance, military police, medical service, and patients with posttraumatic stress disorders.
Results
The 10-item CPSC scale exhibited a one-factorial structure and showed a good internal consistence (Cronbach´s alpha = .86); there were neither ceiling nor bottom effects. The CPSC scores correlated moderately with Positive Life Construction and life satisfaction, and negatively with perceived stress and health affections. Regression analyses indicated that posttraumatic stress disorder symptoms (negative), and the development of effective strategies to deal with disturbing pictures and experiences (positive) were the best predictor of soldiers´ CPSC scores. Soldiers with health affections exhibiting impact upon their daily life had significantly lower CPSC scores than those without impairment (F=8.1; p < .0001).
Conclusions
As core conceptualizations of `mindfulness´ are not necessarily discussed in a military context, the FMI was adopted for military personnel populations, while its two factorial structure with the sub-constructs `acceptance´ and `presence´ was retained. The resulting 10-item CPSC scale had good internal consistence, sound associations with measures of health affections and life satisfaction, and thus can be used as a short and rapid measure in pre-post mission and interventional studies.
doi:10.1186/1752-4458-7-1
PMCID: PMC3558360  PMID: 23289791
Mindfulness; Conscious presence; Soldiers; Trauma; Validation; Questionnaire
5.  Validation of a French version of the Freiburg Mindfulness Inventory - short version: relationships between mindfulness and stress in an adult population 
Background
Whereas interest in incorporating mindfulness into interventions in medicine is growing, data on the relationships of mindfulness to stress and coping in management is still scarce. This report first presents a French validation of the Freiburg Mindfulness Inventory-short form (FMI) in a middle-aged working population. Secondly, it investigates the relationship between psychological adjustment and mindfulness.
Methods
Five hundred and six non-clinical middle-aged working individuals rated themselves on the self-report French version FMI and completed measures of psychological constructs potentially related to mindfulness levels.
Results
Results were comparable to results of the original short version. Internal consistency of the scale based on the one-factor solution was .74, and test-retest reliability was good. The one-dimensional solution as the alternative to the two-factor structure solution yielded suboptimal fit indices. Correlations also indicated that individuals scoring high on mindfulness are prone to stress tolerance, positive affects and higher self-efficacy. Furthermore, subjects with no reports of stressful events were higher on mindfulness.
Conclusion
These data showed that mindfulness can be measured validly and reliably with the proposed French version of the FMI. The data also highlighted the relationship between mindfulness and stress in an adult population. Mindfulness appears to reduce negative appraisals of challenging or threatening events.
doi:10.1186/1751-0759-4-8
PMCID: PMC2927476  PMID: 20704696

Results 1-5 (5)