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Chabal SA, Markwald RR, Chinoy ED. Life onboard a submarine: Sleep, fatigue, and lifestyle behaviors of sailors on a circadian-aligned watchstanding schedule. APPLIED ERGONOMICS 2024; 119:104321. [PMID: 38820921 DOI: 10.1016/j.apergo.2024.104321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 03/11/2024] [Accepted: 05/22/2024] [Indexed: 06/02/2024]
Abstract
This study characterizes, for the first time, the lives of U.S. Navy submariners engaged in normal, sea-based operations while following a circadian-aligned 24-h watchstanding schedule. Fifty-eight submarine crewmembers provided objective (actigraphy) and subjective (questionnaires) sleep data, and information about mood and lifestyle behaviors during 30 days underway. Projected performance scores and estimated circadian phase times were also calculated from actigraphy-based sleep/wake data. Submariners' objective (6.62 ± 0.94 h; mean ± SD) and subjective (5.90 ± 1.38 h) daily sleep quantities while underway were largely comparable to the sleep reportedly received by Sailors across other Navy platforms and watchstanding schedules. Additionally, submariners' actigraphy-predicted circadian phases shifted progressively toward better alignment with watchstanding schedules across time. Nevertheless, subjective sleep quality was low, submariners engaged in unfavorable lifestyle behaviors (lack of regular meals and exercise), and participants reported decreased mood at the completion of their underway time. Recommendations for countermeasure development are provided.
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Affiliation(s)
- Sarah A Chabal
- Naval Submarine Medical Research Laboratory, Groton, CT, USA; Sleep, Tactical Efficiency, and Endurance Laboratory, Warfighter Performance Department, Naval Health Research Center, San Diego, CA, USA; Leidos, Inc., Reston, VA, USA.
| | - Rachel R Markwald
- Sleep, Tactical Efficiency, and Endurance Laboratory, Warfighter Performance Department, Naval Health Research Center, San Diego, CA, USA
| | - Evan D Chinoy
- Sleep, Tactical Efficiency, and Endurance Laboratory, Warfighter Performance Department, Naval Health Research Center, San Diego, CA, USA
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Kerkamm F, Dengler D, Eichler M, Materzok-Köppen D, Belz L, Neumann FA, Zyriax BC, Harth V, Oldenburg M. Sleep Architecture and Sleep-Related Breathing Disorders of Seafarers on Board Merchant Ships: A Polysomnographic Pilot Field Study on the High Seas. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:3168. [PMID: 36833863 PMCID: PMC9962439 DOI: 10.3390/ijerph20043168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 02/02/2023] [Accepted: 02/08/2023] [Indexed: 06/18/2023]
Abstract
As seafarers are assumed to have an increased risk profile for sleep-related breathing disorders, this cross-sectional observational study measured (a) the feasibility and quality of polysomnography (PSG) on board merchant ships, (b) sleep macro- and microarchitecture, (c) sleep-related breathing disorders, such as obstructive sleep apnea (OSA), using the apnea-hypopnea index (AHI), and (d) subjective and objective sleepiness using the Epworth Sleepiness Scale (ESS) and pupillometry. Measurements were carried out on two container ships and a bulk carrier. A total of 19 out of 73 male seafarers participated. The PSG's signal qualities and impedances were comparable to those in a sleep laboratory without unusual artifacts. Compared to the normal population, seafarers had a lower total sleep time, a shift of deep sleep phases in favor of light sleep phases as well as an increased arousal index. Additionally, 73.7% of the seafarers were diagnosed with at least mild OSA (AHI ≥ 5) and 15.8% with severe OSA (AHI ≥ 30). In general, seafarers slept in the supine position with a remarkable frequency of breathing cessations. A total of 61.1% of the seafarers had increased subjective daytime sleepiness (ESS > 5). Pupillometry results for objective sleepiness revealed a mean relative pupillary unrest index (rPUI) of 1.2 (SD 0.7) in both occupational groups. In addition, significantly poorer objective sleep quality was found among the watchkeepers. A need for action with regard to poor sleep quality and daytime sleepiness of seafarers on board is indicated. A slightly increased prevalence of OSA among seafarers is likely.
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Affiliation(s)
- Fiona Kerkamm
- Institute for Occupational and Maritime Medicine Hamburg (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany
| | - Dorothee Dengler
- Institute for Occupational and Maritime Medicine Hamburg (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany
| | - Matthias Eichler
- Institute for Occupational and Maritime Medicine Hamburg (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany
| | - Danuta Materzok-Köppen
- Institute for Occupational and Maritime Medicine Hamburg (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany
| | - Lukas Belz
- Institute for Occupational and Maritime Medicine Hamburg (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany
| | - Felix Alexander Neumann
- Preventive Medicine and Nutrition, Institute for Health Services Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany
| | - Birgit-Christiane Zyriax
- Preventive Medicine and Nutrition, Institute for Health Services Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany
| | - Volker Harth
- Institute for Occupational and Maritime Medicine Hamburg (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany
| | - Marcus Oldenburg
- Institute for Occupational and Maritime Medicine Hamburg (ZfAM), University Medical Center Hamburg-Eppendorf (UKE), 20459 Hamburg, Germany
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van den Berg NH, Michaud X, Pattyn N, Simonelli G. How Sleep Research in Extreme Environments Can Inform the Military: Advocating for a Transactional Model of Sleep Adaptation. Curr Psychiatry Rep 2023; 25:73-91. [PMID: 36790725 DOI: 10.1007/s11920-022-01407-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/06/2022] [Indexed: 02/16/2023]
Abstract
PURPOSE OF REVIEW We review the literature on sleep in extreme environments. Accordingly, we present a model that identifies the need for mitigating interventions to preserve sleep quality for military deployments. RECENT FINDINGS Situational factors that affect sleep in extreme environments include cold temperatures, isolated and confined areas, fluctuating seasonality, photoperiodicity, and extreme latitudes and altitudes. Results vary across studies, but general effects include decreased total sleep time, poor sleep efficiency, and non-specific phase delays or phase advances in sleep onset and sleep architecture. Considering habitability measures (e.g., light or temperature control) and individual differences such as variable stress responses or sleep need can mitigate these effects to improve mood, cognition, and operational performance. Although the situational demands during military missions inevitably reduce total sleep time and sleep efficiency, mitigating factors can attenuate sleep-related impairments, hence allowing for optimal mission success and personnel safety.
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Affiliation(s)
- N H van den Berg
- Centre d'études avancées en médecine du sommeil, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord de l'Île-de-Montréal, Montreal, Quebec, Canada.,School of Psychology, Faculty of Social Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - X Michaud
- Centre d'études avancées en médecine du sommeil, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord de l'Île-de-Montréal, Montreal, Quebec, Canada.,Department of Psychology, Faculty of Arts and Science, Université de Montréal, Montreal, Quebec, Canada
| | - N Pattyn
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.,Human Physiology Department (MFYS), Vrije Universiteit Brussel, Brussels, Belgium.,VIPER Research Unit, Royal Military Academy, Brussels, Belgium
| | - G Simonelli
- Centre d'études avancées en médecine du sommeil, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord de l'Île-de-Montréal, Montreal, Quebec, Canada. .,Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada. .,Department of Neuroscience, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.
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Corrigan SL, Roberts SSH, Warmington SA, Drain JR, Tait JL, Bulmer S, Main LC. Overnight heart rate variability responses to military combat engineer training. APPLIED ERGONOMICS 2023; 107:103935. [PMID: 36371929 DOI: 10.1016/j.apergo.2022.103935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 10/28/2022] [Accepted: 10/29/2022] [Indexed: 06/16/2023]
Abstract
The study aimed to determine if overnight heart rate variability (HRV) is reflective of workload and stress during military training. Measures of cognitive load, perceived exertion, physical activity, nocturnal HRV, cognitive performance and sleep were recorded for a 15-day assessment period in 32 combat engineers. The assessment period consisted of 4 phases, PRE, FIELD, BASE and RECOVERY that exposed trainees to periods of sleep deprivation and restriction. The FIELD phase was characterised by an increase in mood disturbance, perceived exertion, physical activity, HRV and a reduction in sleep quantity (p < 0.05). Measures of HRV returned to PRE-values quicker than subjective wellbeing responses. The combination of sleep duration (β = -0.002, F = 13.42, p < 0.001) and physical activity (metabolic equivalents, β = -0.483, F = 5.95, p = 0.017), the main stressors of the exercise, provided a significant effect in the best predictive model of HRV. The different recovery rates of HRV and subjective wellbeing suggest a different physiological and psychological response.
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Affiliation(s)
- Sean L Corrigan
- Deakin University, Centre for Sport Research, Geelong, Victoria, Australia.
| | | | - Stuart A Warmington
- Deakin University, Institute for Physical Activity and Nutrition, Geelong, Victoria, Australia
| | - Jace R Drain
- Defence Science and Technology Group, Fishermans Bend, Victoria, Australia
| | - Jamie L Tait
- Deakin University, Institute for Physical Activity and Nutrition, Geelong, Victoria, Australia
| | - Sean Bulmer
- Deakin University, Centre for Sport Research, Geelong, Victoria, Australia
| | - Luana C Main
- Deakin University, Institute for Physical Activity and Nutrition, Geelong, Victoria, Australia
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Bulmer S, Corrigan SL, Drain JR, Tait JL, Aisbett B, Roberts S, Gastin PB, Main LC. Characterising Psycho-Physiological Responses and Relationships during a Military Field Training Exercise. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:14767. [PMID: 36429484 PMCID: PMC9690080 DOI: 10.3390/ijerph192214767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 10/28/2022] [Accepted: 11/01/2022] [Indexed: 06/16/2023]
Abstract
UNLABELLED Over a 15-day period, that included an eight-day field trial, the aims of this study were to (1) quantify the physical workload, sleep and subjective well-being of soldiers in training; (2a) Explore relationships between workload and well-being, and (2b) sleep and well-being; (3) Explore relationships between workload, sleep, and well-being. METHODS Sixty-two Combat Engineer trainees (59 male, 3 female; age: 25.2 ± 7.2 years) wore an ActiGraph GT9X to monitor daily energy expenditure, physical activity, and sleep. Rating of perceived exertion (RPE), sleep quality, and fatigue were measured daily, subjective well-being was reported days 1, 5, 9, 13 and 15. Multi-level models were used for the analysis. RESULTS Well-being was affected by a combination of variables including workload, subjective sleep quality, sleep duration, and sleep efficiency. RPE and subjective sleep quality were consistently significant parameters within the models of best fit. CONCLUSIONS Perceptions of well-being were lower during the field training when physical workload increased, and sleep decreased. Energy expenditure was comparatively low, while daily sleep duration was consistent with field training literature. Subjective assessments of workload and sleep quality were consistently effective in explaining variations in well-being and represent an efficient approach to monitor training status of personnel.
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Affiliation(s)
- Sean Bulmer
- Deakin University, Centre for Sport Research, School of Exercise and Nutrition Sciences, Geelong, VIC 3220, Australia
| | - Sean L. Corrigan
- Deakin University, Centre for Sport Research, School of Exercise and Nutrition Sciences, Geelong, VIC 3220, Australia
| | - Jace R. Drain
- Defence Science and Technology Group, Fisherman’s Bend, Melbourne, VIC 3207, Australia
| | - Jamie L. Tait
- Deakin University, Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Geelong, VIC 3220, Australia
| | - Brad Aisbett
- Deakin University, Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Geelong, VIC 3220, Australia
| | - Spencer Roberts
- Deakin University, Centre for Sport Research, School of Exercise and Nutrition Sciences, Geelong, VIC 3220, Australia
| | - Paul B. Gastin
- La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, Human Services and Sport, La Trobe University, Bundoora, VIC 3086, Australia
| | - Luana C. Main
- Deakin University, Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Geelong, VIC 3220, Australia
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Corrigan SL, Bulmer S, Roberts SSH, Warmington S, Drain J, Main LC. Monitoring Responses to Basic Military Training with Heart Rate Variability. Med Sci Sports Exerc 2022; 54:1506-1514. [PMID: 35394465 DOI: 10.1249/mss.0000000000002930] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Heart rate variability (HRV) has shown sensitivity to the acute stressors experienced by defence personnel. This study examines the suitability of overnight HRV as a repeated measure of allostatic load in defence personnel. METHODS Daily measures of sleep, cognitive load and perceived exertion were reported for the 12-week duration of basic military training (BMT) in 48 recruits. Measures of physical activity, subjective wellbeing and HRV were measured weekly. The natural log of the root mean square of successive differences of inter-beat intervals (Ln RMSSD) and the Ln RMSSD to inter-beat interval ratio (Ln RMSSD:RRi ratio) during predicted slow wave sleep were used for HRV. Physical performance was assessed via the 20-m shuttle run and maximal push-up test in week two and eight of BMT with predicted V̇O2 peak values calculated. RESULTS Predicted V̇O2 peak increased from 42.6 ± 4.5 to 48.0 ± 2.7 mL·kg·min (p < 0.001). Ln RMSSD was elevated in week seven and ten and the Ln RMSSD:RRi ratio was elevated in week ten above all other weeks (p < 0.05). An increase in perceived exertion (F = 9.10, p = 0.003) and subjective fatigue (F = 6.97, p = 0.009), as well as a reduction in V̇O2 peak (F = 7.95, p = 0.009), individually predicted an increase in Ln RMSSD. The best predictive model of Ln RMSSD included perceived exertion (F = 8.16, p = 0.005), subjective fatigue (F = 8.49, p = 0.004), the number of awakenings during sleep (F = 7.79, p = 0.006) and the change in V̇O2 peak (F = 19.110, p < 0.001). CONCLUSIONS HRV was predicted by subjective recruit responses to BMT workloads rather than objective measures of physical activity. Improvements in cardiorespiratory fitness depicted recruits who experienced enough stress to facilitate physiological adaptation which was reflected by a reduction in HRV during BMT. Monitoring HRV and HRV in relation to inter-beat interval length may provide a better tool for determining allostatic load than HRV alone.
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Affiliation(s)
- Sean L Corrigan
- Deakin University, Centre for Sport Research, Geelong, Victoria, AUSTRALIA
| | - Sean Bulmer
- Deakin University, Centre for Sport Research, Geelong, Victoria, AUSTRALIA
| | | | - Stuart Warmington
- Deakin University, Institute for Physical Activity and Nutrition, Geelong, Victoria, AUSTRALIA
| | - Jace Drain
- Defence Science and Technology Group, Fishermans Bend, Victoria, AUSTRALIA
| | - Luana C Main
- Deakin University, Institute for Physical Activity and Nutrition, Geelong, Victoria, AUSTRALIA
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Bulmer S, Aisbett B, Drain JR, Roberts S, Gastin PB, Tait J, Main LC. Sleep of recruits throughout basic military training and its relationships with stress, recovery, and fatigue. Int Arch Occup Environ Health 2022; 95:1331-1342. [PMID: 35226165 PMCID: PMC9273528 DOI: 10.1007/s00420-022-01845-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 02/14/2022] [Indexed: 12/22/2022]
Abstract
Objective Studies in basic military training (BMT) examining sleep are largely cross-sectional, and do not investigate relationships between sleep, stress, recovery and fatigue. The aims of this study were to (1a) quantify changes in recruits’ sleep quantity and quality over 12 weeks of BMT; (1b) quantify changes in recruits’ perceptions of stress, fatigue and recovery over BMT; and (2) explore relationships between sleep, and perceptions of stress, fatigue and recovery. Methods 45 recruits (37 male; 8 female, age: 25.2 ± 7.2 years, height: 176.2 ± 10.0 cm, mass: 76.8 ± 15.0 kg) wore ActiGraph GT9X’s for 12 weeks of BMT, collecting sleep duration, efficiency and awakenings. Subjective sleep quality, fatigue were measured daily, with stress and recovery measured weekly. Multi-level models assessed relationships between sleep, and stress, recovery, and fatigue. Results Objective daily means for sleep duration were 6.3 h (± 1.2 h) and 85.6% (± 5.5%) for sleep efficiency. Main effects were detected for all mean weekly values (p < 0.05). Sleep quality showed the strongest relationships with stress, recovery and fatigue. The best model to explain relationships between, stress, recovery and fatigue, included sleep quality, sleep duration, sleep efficiency and awakenings. Conclusions The reported mean sleep duration of 6.3 h per night may negatively impact training outcomes across BMT. Combining both subjective and objective measures of sleep best explained relationships between sleep metrics stress, fatigue and recovery. Perceived sleep quality was most strongly related to change in stress, recovery, or post-sleep fatigue.
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Affiliation(s)
- Sean Bulmer
- School of Exercise and Nutrition Sciences, Deakin University, Centre for Sport Research, Geelong, VIC, Australia
| | - Brad Aisbett
- School of Exercise and Nutrition Sciences, Deakin University, Institute for Physical Activity and Nutrition, 221 Burwood Highway, Burwood, Geelong, VIC, 3125, Australia
| | - Jace R Drain
- Defence Science and Technology Group, Fisherman's Bend, Melbourne, Australia
| | - Spencer Roberts
- School of Exercise and Nutrition Sciences, Deakin University, Institute for Physical Activity and Nutrition, 221 Burwood Highway, Burwood, Geelong, VIC, 3125, Australia
| | - Paul B Gastin
- School of Allied Health, Human Services and Sport, La Trobe University, La Trobe Sport and Exercise Medicine Research Centre, Melbourne, VIC, Australia
| | - Jamie Tait
- School of Exercise and Nutrition Sciences, Deakin University, Institute for Physical Activity and Nutrition, 221 Burwood Highway, Burwood, Geelong, VIC, 3125, Australia
| | - Luana C Main
- School of Exercise and Nutrition Sciences, Deakin University, Institute for Physical Activity and Nutrition, 221 Burwood Highway, Burwood, Geelong, VIC, 3125, Australia.
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Measurement Methods of Fatigue, Sleepiness, and Sleep Behaviour Aboard Ships: A Systematic Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 19:ijerph19010120. [PMID: 35010383 PMCID: PMC8750891 DOI: 10.3390/ijerph19010120] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/17/2021] [Accepted: 12/20/2021] [Indexed: 11/17/2022]
Abstract
Since seafarers are known to be exposed to numerous job-related stress factors that can cause fatigue, sleepiness, and disturbed sleep behaviour, the aim of this review was to provide an overview of the subjective and objective measurement methods of these strains. Using a systematic review, 166 studies were identified within the period of January 2010 to December 2020 using the PubMed database. Of the 21 studies selected, 13 used both subjective and objective measurement methods. Six studies used only subjective and two studies only objective methods. For subjective assessment, 12 different questionnaires could be identified as well as activity and sleeping logs. Actigraphy and reaction time tests (RTT) were the most common objective methods. In single cases, electrooculography (EOG), pupillometry and ambulatory polysomnography (PSG) were used. Measurement-related limitations due to vessel-related impacts were less often reported than expected. No restrictions of daily routines on board were described, and only single-measurement disturbances due to ship movements were mentioned. The present literature review reveals that there are various routines to measure fatigue, sleepiness, and sleep behaviour on board. A combination of subjective and objective methods often appears to be beneficial. The frequent use of actigraphy and RTT on board suggests good feasibility and reliable measurements with these methods. The use of ambulatory PSG in maritime-like contexts suggests that this method would also be feasible on board.
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Jaipurkar R, Mahapatra SS, Bobdey S, Banerji C. Work-rest pattern, alertness and performance assessment among naval personnel deployed at sea: A cross sectional study. Med J Armed Forces India 2019; 75:158-163. [PMID: 31065184 DOI: 10.1016/j.mjafi.2018.01.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 01/16/2018] [Indexed: 10/27/2022] Open
Abstract
Background The combat naval vessels require continuous operational preparedness for guarding the vast coastline. Sailors onboard these ships are at risk for sleep deprivation. Sailors may be vulnerable to chronic fatigue; and decreased performance, vigilance, and cognitive functioning owing to sleep debt, which may affect safety during tactical operations and while transportation of ships. In this study we assessed the work-rest pattern and level of alertness during sailing and non sailing days. Methods Thirty-two male participants maintained a 24-h sleep and activity log for 5 days. Furthermore, qualitative gross motor activity was recorded using an actiwatch during these 5 days. Participants also completed four test sessions of personal digital assistant (PDA) based psychomotor vigilance task (PVT) test: pre-sleep, post-sleep, pre-work, and post-work. A comparison of data was performed using the Wilcoxon signed-rank test. Results Sailors received approximately 1 h less of rest while sailing. There was a significant difference in bedtime, wake-up time, total sleep time, sleep onset latency (SOL), wake up after sleep onset (WASO), and the number of awakenings during the non-sailing and the sailing days. PVT data showed significantly higher reaction times during the sailing days on pre-work and post-sleep sessions. Conclusion Our study shows that although the sailors are not getting sufficient restorative sleep while sailing as compared to non-sailing days, this is not affecting their cognitive functioning while working.
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Affiliation(s)
- Raksha Jaipurkar
- Associate Professor, Department of Physiology, Armed Forces Medical College, Pune, 411040 India
| | - S S Mahapatra
- Head of Department, Space and Environmental Physiology, Institute of Aerospace Medicine, Bengaluru, India
| | - Saurabh Bobdey
- Classified Specialist (Community Medicine), O/o DGMS (Navy), New Delhi, India
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Wenigmann M, Gorzka RJ, Garling M, Spiegelhalder K, Höllmer H, Schulz H. Sleep state misperception in psychiatric patients. SOMNOLOGIE 2018. [DOI: 10.1007/s11818-018-0181-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Hernández LM, Markwald RR, Kviatkovsky SA, Perry LN, Taylor MK. Morning Cortisol Is Associated With Stress and Sleep in Elite Military Men: A Brief Report. Mil Med 2018; 183:e255-e259. [PMID: 29660025 DOI: 10.1093/milmed/usy047] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/13/2017] [Accepted: 03/06/2018] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Accumulating evidence suggests that trends in salivary cortisol after awakening may be reliable biological predictors of morbidity and mortality. In a sample of elite military men, our lab recently established summary parameters of morning cortisol as well as their stability across 2 d of repeated sampling. MATERIALS AND METHODS In this follow-on study, we evaluated summary parameters and their relationships to theoretically relevant demographic (i.e., age, body mass index) and biobehavioral correlates (i.e., blood pressure [BP], sleep parameters, fatigue, and perceived stress). Fifty-eight male active duty U.S. Navy SEALs self-collected salivary samples on 2 consecutive, midweek workdays upon waking (WAKE), WAKE+30 min, WAKE+60 min, 4 p.m., and 9 p.m. in a nondeployed, free-living setting. Resting BP was measured manually, and sleep-wake periods were objectively derived using actigraphy. Daily fatigue and perceived stress were measured by self-report. Summary parameters of morning cortisol magnitude (i.e., peak value [Peak], area under the curve in terms of ground [AUCG], and average of morning samples [AVE]) were assessed with respect to each demographic and biobehavioral item via correlational analyses. A subgroup of 29 participants was selected for compliance with salivary sampling in the morning across 2 d. RESULTS Perceived stress was positively associated with Peak (r[27] = 0.437, p < 0.05), AUCG (r[25] = 0.500, p < 0.01), and AVE (r[25] = 0.506, p < 0.01). Total sleep time was also positively associated with Peak (r[26] = 0.378, p < 0.05). There were borderline associations between some summary parameters and diastolic BP, percent sleep, and wake after sleep onset. Age, systolic BP, body mass index, time in bed, sleep efficiency, and fatigue did not associate with morning cortisol. CONCLUSIONS Preliminary evidence of morning cortisol summary parameters as biobehavioral indicators was established, and these parameters appeared to associate with stress and sleep in elite military men.
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Affiliation(s)
- Lisa M Hernández
- Department of Warfighter Performance, Naval Health Research Center, 140 Sylvester Road, San Diego, CA
| | - Rachel R Markwald
- Department of Warfighter Performance, Naval Health Research Center, 140 Sylvester Road, San Diego, CA
| | - Shiloah A Kviatkovsky
- Department of Warfighter Performance, Naval Health Research Center, 140 Sylvester Road, San Diego, CA
| | - Lori N Perry
- Department of Warfighter Performance, Naval Health Research Center, 140 Sylvester Road, San Diego, CA
| | - Marcus K Taylor
- Department of Warfighter Performance, Naval Health Research Center, 140 Sylvester Road, San Diego, CA
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Taylor MK, Hernández LM, Kviatkovsky SA, Schoenherr MR, Stone MS, Sargent P. The "yin and yang" of the adrenal and gonadal systems in elite military men. Stress 2017. [PMID: 28629254 DOI: 10.1080/10253890.2017.1333594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
We recently established daily, free-living profiles of the adrenal hormone cortisol, the (primarily adrenal) anabolic precursor dehydroepiandrosterone (DHEA) and the (primarily gonadal) anabolic hormone testosterone in elite military men. A prevailing view is that adrenal and gonadal systems reciprocally modulate each other; however, recent paradigm shifts prompted the characterization of these systems as parallel, cooperative processes (i.e. the "positive coupling" hypothesis). In this study, we tested the positive coupling hypothesis in 57 elite military men by evaluating associations between adrenal and gonadal biomarkers across the day. Salivary DHEA was moderately and positively coupled with salivary cortisol, as was salivary testosterone. Anabolic processes (i.e. salivary DHEA and testosterone) were also positively and reliably coupled across the day. In multivariate models, salivary DHEA and cortisol combined to account for substantial variance in salivary testosterone concentrations across the day, but this was driven almost exclusively by DHEA. This may reflect choreographed adrenal release of DHEA with testicular and/or adrenal release of testosterone, systemic conversion of DHEA to testosterone, or both. DHEA and testosterone modestly and less robustly predicted cortisol concentrations; this was confined to the morning, and testosterone was the primary predictor. Altogether, top-down co-activation of adrenal and gonadal hormone secretion may complement bottom-up counter-regulatory functions to foster anabolic balance and neuronal survival; hence, the "yin and yang" of adrenal and gonadal systems. This may be an adaptive process that is amplified by stress, competition, and/or dominance hierarchy.
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Affiliation(s)
- Marcus K Taylor
- a Biobehavioral Sciences Lab, Warfighter Performance Department , Naval Health Research Center , San Diego , CA , USA
| | - Lisa M Hernández
- a Biobehavioral Sciences Lab, Warfighter Performance Department , Naval Health Research Center , San Diego , CA , USA
| | - Shiloah A Kviatkovsky
- a Biobehavioral Sciences Lab, Warfighter Performance Department , Naval Health Research Center , San Diego , CA , USA
| | - Matthew R Schoenherr
- a Biobehavioral Sciences Lab, Warfighter Performance Department , Naval Health Research Center , San Diego , CA , USA
| | - Michael S Stone
- b College of Health and Human Services , Purdue University , West Lafayette , IN , USA
| | - Paul Sargent
- c Naval Special Warfare Group ONE , San Diego , CA , USA
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Taylor MK, Kviatkovsky SA, Hernández LM, Sargent P, Segal S, Granger DA. Anabolic hormone profiles in elite military men. Steroids 2016; 110:41-48. [PMID: 27083310 DOI: 10.1016/j.steroids.2016.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/29/2016] [Accepted: 04/05/2016] [Indexed: 01/26/2023]
Abstract
We recently characterized the awakening responses and daily profiles of the catabolic stress hormone cortisol in elite military men. Anabolic hormones follow a similar daily pattern and may counteract the catabolic effects of cortisol. This companion report is the first to characterize daily profiles of anabolic hormones dehydroepiandrosterone (DHEA) and testosterone in this population. Overall, the men in this study displayed anabolic hormone profiles comparable to that of healthy, athletic populations. Consistent with the cortisol findings in our prior report, summary parameters of magnitude (hormone output) within the first hour after awakening displayed superior stability versus summary parameters of pattern for both DHEA (r range: 0.77-0.82) and testosterone (r range: 0.62-0.69). Summary parameters of evening function were stable for the two hormones (both p<0.001), while the absolute decrease in testosterone across the day was a stable proxy of diurnal function (p<0.001). Removal of noncompliant subjects did not appreciably affect concentration estimates for either hormone at any time point, nor did it alter the repeatability of any summary parameter. The first of its kind, this report enables accurate estimations of anabolic balance and resultant effects upon health and human performance in this highly resilient yet chronically stressed population.
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Affiliation(s)
- Marcus K Taylor
- Biobehavioral Sciences Lab, Warfighter Performance Department, Naval Health Research Center, 140 Sylvester Road, San Diego, CA 92106-3521, United States; Department of Exercise and Nutritional Sciences, San Diego State University, ENS Building, Room 351, 5500 Campanile Drive, San Diego, CA 92182, United States; Institute for Interdisciplinary Salivary Bioscience Research, Arizona State University, 550 E. Orange Street, Tempe, AZ 85287, United States.
| | - Shiloah A Kviatkovsky
- Biobehavioral Sciences Lab, Warfighter Performance Department, Naval Health Research Center, 140 Sylvester Road, San Diego, CA 92106-3521, United States
| | - Lisa M Hernández
- Biobehavioral Sciences Lab, Warfighter Performance Department, Naval Health Research Center, 140 Sylvester Road, San Diego, CA 92106-3521, United States; Department of Exercise and Nutritional Sciences, San Diego State University, ENS Building, Room 351, 5500 Campanile Drive, San Diego, CA 92182, United States
| | - Paul Sargent
- Naval Special Warfare Group ONE, 3632 Guadalcanal Road, Building 165, San Diego, CA 92155, United States
| | - Sabrina Segal
- Department of Psychology, Arizona State University, 550 E. Orange Street, Tempe, AZ 85287, United States
| | - Douglas A Granger
- Johns Hopkins School of Nursing and Bloomberg School of Public Health, 3400 North Charles Street, Baltimore, MD 21218, United States; Institute for Interdisciplinary Salivary Bioscience, University of California - Irvine, Irvine, CA 92697, United States; Salivary Bioscience Laboratory and Department of Psychology, University of Nebraska, 1400 R. Street, Lincoln, NE, United States
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