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The impact of sleep restriction while performing simulated physical firefighting work on cortisol and heart rate responses

  • Alexander WolkowEmail author
  • Brad Aisbett
  • John Reynolds
  • Sally A. Ferguson
  • Luana C. Main
Original Article

Abstract

Purpose

Physical work and sleep restriction are two stressors faced by firefighters, yet the combined impact these demands have on firefighters’ acute stress responses is poorly understood. The purpose of the present study was to assess the effect firefighting work and sleep restriction have on firefighters’ acute cortisol and heart rate (HR) responses during a simulated 3-day and 2-night fire-ground deployment.

Methods

Firefighters completed multiple days of simulated physical work separated by either an 8-h (control condition; n = 18) or 4-h sleep opportunity (sleep restriction condition; n = 17). Salivary cortisol was sampled every 2 h, and HR was measured continuously each day.

Results

On day 2 and day 3 of the deployment, the sleep restriction condition exhibited a significantly higher daily area under the curve cortisol level and an elevated cortisol profile in the afternoon and evening when compared with the control condition. Firefighters’ HR decreased across the simulation, but there were no significant differences found between conditions.

Conclusion

Findings highlight the protective role an 8-h sleep opportunity between shifts of firefighting work has on preserving normal cortisol levels when compared to a 4-h sleep opportunity which resulted in elevated afternoon and evening cortisol. Given the adverse health outcomes associated with chronically high cortisol, especially later in the day, future research should examine how prolonged exposure to firefighting work (including restricted sleep) affects firefighters’ cortisol levels long term. Furthermore, monitoring cortisol levels post-deployment will determine the minimum recovery time firefighters need to safely return to the fire-ground.

Keywords

Firefighters Stress Sleep restriction Physical work Cortisol Heart rate 

Notes

Acknowledgments

The authors would like to acknowledge the Bushfire Co-operative Research Centre for providing the financial support for this project. We would also like to thank the firefighters that volunteered their time to participate in this study.

Compliance with ethical standards

Conflict of interest

The authors have no conflicts of interest to declare.

Ethical standard

The procedures performed in this study that involved human participants were in accordance with the ethical standards of the institution and the 1964 Helsinki Declaration and its later amendments.

References

  1. Adam EK, Kumari M (2009) Assessing salivary cortisol in large-scale, epidemiological research. Psychoneuroendocrinology 34:1423–1436CrossRefGoogle Scholar
  2. Aisbett B, Phillips M, Raines J, Nichols D (2007) Work patterns of tanker-based bushfire suppression by Australian volunteer firefighters in south-east Australia. In: Human dimensions of wildfire conference, Fort Collins, ColoradoGoogle Scholar
  3. Aisbett B, Wolkow A, Sprajcer M, Ferguson S (2012) “Awake, smoky, and hot”: providing an evidence-base for managing the risks associated with occupational stressors encountered by wildland firefighters. Appl Ergon 43:916–925CrossRefGoogle Scholar
  4. An S-J, Chung YK, Kim BH, Kwak KM, Son J-S, Koo J-W, Ju Y-S, Kwon Y-J (2015) The effect of organisational system on self-rated depression in a panel of male municipal firefighters. Ann Occup Environ Med 27:1. doi: 10.1186/s40557-014-0044-x CrossRefGoogle Scholar
  5. Andersen JP, Silver RC, Stewart B, Koperwas B, Kirschbaum C (2013) Psychological and physiological responses following repeated peer death. PLoS One 8:e75881. doi: 10.1371/journal.pone.0075881 CrossRefGoogle Scholar
  6. Austin-Ketch TL, Violanti J, Fekedulegn D, Andrew ME, Burchfiel C, Hartley T, Vena JE (2010) Metabolic syndrome and salivary cortisol: is there dysregulation among a group of active duty urban police officers? Diabet Metab Syndr Clin Res Rev 4:82–88CrossRefGoogle Scholar
  7. Baty JJ, Hyonson H, Zhenping D, Bernard JR, Bei W, Bongan K, Ivy JL (2007) The effect of a carbohydrate and protein supplement on resistance exercise performance, hormonal response and muscle damage. J Strength Cond Res (Allen Press Publishing Services Inc.) 21:321–329Google Scholar
  8. Bierwolf C, Struve K, Marshall L, Born J, Fehm HL (1997) Slow wave sleep drives inhibition of pituitary-adrenal secretion in humans. J Neuroendocrinol 9:479–484CrossRefGoogle Scholar
  9. Biopharmaceutics Coordinating Committee (2001) Bioanalytical method validation. In: Centre for Drug Evaluation and Research (ed) Guidance for industry. Center for Veterinary Medicine (CVM), Food and Drug AdministrationGoogle Scholar
  10. Branth S (2006) Energy metabolic stress syndrome: impact of physical activity of different intensity and duration. In: digital comprehensive summaries of Uppsala dissertations from the faculty of medicine 209. Uppsala UniversityGoogle Scholar
  11. Brose A, Schmiedek F, Lövdén M, Lindenberger U (2012) Daily variability in working memory is coupled with negative affect: the role of attention and motivation. Emotion 12:605–617. doi: 10.1037/a0024436 CrossRefGoogle Scholar
  12. Brunner EJ, Hemingway H, Walker BR, Page M, Clarke P, Juneja M, Shipley MJ, Kumari M, Andrew R, Seckl JR, Papadopoulos A, Checkley S, Rumley A, Lowe GDO, Stansfeld SA, Marmot MG (2002) Adrenocortical, autonomic, and inflammatory causes of the metabolic syndrome: nested case-control study. Circulation 106:2659–2665CrossRefGoogle Scholar
  13. Budd GM, Brotherhood JR, Hendrie AL, Jeffery SE, Beasley FA, Costin BP, Wu Z, Baker MM, Cheney NP, Dawson MP (1997) Project aquarius 7. Physiological and subjective responses of men suppressing wildland fire. Int J Wildland Fire 7:133–144CrossRefGoogle Scholar
  14. Burnham KP, Anderson DR (2002) Model selection and multi-model inference: a practical information-theoretic approach, 2nd edn. Springer, New YorkGoogle Scholar
  15. Buxton OM, Pavlova M, Reid EW, Wei W, Simonson DC, Adler GK (2010) Sleep restriction for 1 week reduces insulin sensitivity in healthy men. Diabetes 59:2126–2133. doi: 10.2337/db09-0699 CrossRefGoogle Scholar
  16. Carey MG, Al-Zaiti SS, Dean GE, Sessanna L, Finnell DS (2011) Sleep problems, depression, substance use, social bonding, and quality of life in professional firefighters. J Occup Environ Med Am Coll Occup Environ Med 53:928–933. doi: 10.1097/JOM.0b013e318225898f CrossRefGoogle Scholar
  17. Cater H, Clancy D, Duffy K, Holgate A, Wilison B (2007) Wood J Fatigue on the fireground: the DPI experience. In: Thornton RE (ed) Australasian fire authorities council/bushfire co-operative research centre annual conference. Hobart, Grand ChancellorGoogle Scholar
  18. Chandola T, Heraclides A, Kumari M (2010) Psychophysiological biomarkers of workplace stressors. Neurosci Biobehav Rev 35:51–57CrossRefGoogle Scholar
  19. Cook B, Mitchell W (2013) Occupational health effects for firefighters: the extent and implications of physical and psychological injuries. Report prepared for the United Firefighters Union of Australia, Victorian Branch, Centre of Full Employment and Equity, The University of Newcastle, Callaghan, NSWGoogle Scholar
  20. Cook C, Beaven CM, Kilduff LP, Drawer S (2012) Acute caffeine ingestion’s increase of voluntarily chosen resistance-training load after limited sleep. Int J Sport Nutr Exerc Metab 22:157–164Google Scholar
  21. Cuddy JS, Gaskill SE, Sharkey BJ, Harger SG, Ruby BC (2007) Supplemental feedings increase self-selected work output during wildfire suppression. Med Sci Sports Exerc 39:1004–1012CrossRefGoogle Scholar
  22. Cullen T, Thomas AW, Webb R, Hughes MG (2015) The relationship between interleukin-6 in saliva, venous and capillary plasma, at rest and in response to exercise. Cytokine. doi: 10.1016/j.cyto.2014.10.011 Google Scholar
  23. Dabrowski J (2008) Work stress and coronary heart disease: what are the mechanisms? Eur Heart J 29:640–648. doi: 10.1093/eurheartj/ehm584 CrossRefGoogle Scholar
  24. Dabrowski J, Ziemba A, Tomczak A, Mikulski T (2012) Physical performance of healthy men exposed to long exercise and sleep deprivation. Med Sport 16:6–11Google Scholar
  25. Dallman M, Strack A, Akana S, Bradbury M, Hanson E (1993) Feast and Famine: critical role of glucocorticoids with insulin in daily energy flow. Front Neuroendocrinol 14:303–347CrossRefGoogle Scholar
  26. Desantis AS, Diezroux AV, Hajat A, Aiello AE, Golden SH, Jenny NS, Seeman TE, Shea S (2012) Associations of salivary cortisol levels with inflammatory markers: the multi-ethnic study of atherosclerosis. Psychoneuroendocrinology 37:1009–1018. doi: 10.1016/j.psyneuen.2011.11.009 CrossRefGoogle Scholar
  27. Dettoni JL, Consolim-Colombo FM, Drager LF, Rubira MC, Cavasin de Souza SBP, Irigoyen MC, Mostarda C, Borile S, Krieger EM, Moreno H Jr, Lorenzi-Filho G (2012) Cardiovascular effects of partial sleep deprivation in healthy volunteers. J Appl Physiol (Bethesda, MD: 1985) 113:232–236. doi: 10.1152/japplphysiol.01604.2011 CrossRefGoogle Scholar
  28. Fahs CA, Huimin Y, Ranadive S, Rossow LM, Agiovlasitis S, Echols G, Smith D, Horn GP, Rowland T, Lane A, Fernhall B (2011) Acute effects of firefighting on arterial stiffness and blood flow. Vasc Med 16:113–118. doi: 10.1177/1358863x11404940 CrossRefGoogle Scholar
  29. Faulkner SH, Spilsbury KL, Harvey J, Jackson A, Huang J, Platt M, Tok A, Nimmo MA (2014) The detection and measurement of interleukin-6 in venous and capillary blood samples, and in sweat collected at rest and during exercise. Eur J Appl Physiol 114:1207–1216. doi: 10.1007/s00421-014-2851-8 CrossRefGoogle Scholar
  30. Fellmann N, Bedu M, Boudet G, Mage M, Sagnol M, Pequignot JM, Claustrat B, Brun J, Peyrin L, Coudert J (1992) Inter-relationships between pituitary-adrenal hormones and catecholamines during a 6-day Nordic ski race. Eur J Appl Physiol 64:258–265CrossRefGoogle Scholar
  31. Ferguson SA, Aisbett B, Jay SM, Onus K, Lord C, Sprajcer M, Thomas MJ (2011) Design of a valid simulation for researching physical, physiological and cognitive performance in volunteer firefighters during bushfire deployment. Paper presented at the Australasian Fire Authorities/Bushfire Co-Operative Research Center Annual Conference, SydneyGoogle Scholar
  32. Food and Agricultural Organization (2004) Report on human energy requirements. In: Food and Agriculture Organization/World Health Organisation/United Nations University Expert Consultation (ed). RomeGoogle Scholar
  33. Glass D, Sim M, Pircher S, Del Monaco A, Dimitriadis C, Miosge J, Vander Hoorn S, Gordon I (2014) Australian firefighters’ health study full report. Monash, Centre for Occupational and Environmental Health, MelbourneGoogle Scholar
  34. Gleeson M, Blannin AK, Walsh NP, Bishop NC, Clark AM (1998) Effect of low- and high-carbohydrate diets on the plasma glutamine and circulating leukocyte responses to exercise. Int J Sport Nutr 8:49–59Google Scholar
  35. Glickman-Weiss EL, Hegsted M, Nelson AG, Hearon CM, Dunbar CC, Tulley R (1995) A comparison of a carbohydrate-electrolyte beverage versus a placebo beverage in maintaining thermoregulatory and blood homeostasis during the training of firefighters. Wilderness Environ Med 6:377–384CrossRefGoogle Scholar
  36. Goh VH, Tong TY, Lim C, Low EC, Lee LK (2001) Effects of one night of sleep deprivation on hormone profiles and performance efficiency. Mil Med 166:427–431Google Scholar
  37. Golden S, Wand G, Malhotra S, Kamel I, Horton K (2011) Reliability of hypothalamic–pituitary–adrenal axis assessment methods for use in population-based studies. Eur J Epidemiol 26:511–525CrossRefGoogle Scholar
  38. Gundersen Y, Opstad P, Reistad T, Thrane I, Vaagenes P (2006) Seven days’ around the clock exhaustive physical exertion combined with energy depletion and sleep deprivation primes circulating leukocytes. Eur J Appl Physiol 97:151–157CrossRefGoogle Scholar
  39. Gurrin LC, Scurrah KJ, Hazelton ML (2005) Tutorial in biostatistics: spline smoothing with linear mixed models. Stat Med 24:3361–3381CrossRefGoogle Scholar
  40. Hajat A, Diez-Roux AV, Sanchez BN, Holvoet P, Lima JA, Merkin SS, Polak JF, Seeman TE, Wu MH (2013) Examining the association between salivary cortisol levels and subclinical measures of atherosclerosis: the multi-ethnic study of atherosclerosis. Psychoneuroendocrinolgy 38:1036–1046CrossRefGoogle Scholar
  41. Harris TO, Borsanyi S, Messari S, Stanford K, Cleary SE, Shiers HM, Brown GW, Herbert J (2000) Morning cortisol as a risk factor for subsequent major depressive disorder in adult women. Br J Psychiatry 177:505–510CrossRefGoogle Scholar
  42. Hjemdahl P (1993) Plasma catecholamines–analytical challenges and physiological limitations. Baillière’s Clin Endocrinol Metab 7:307–353CrossRefGoogle Scholar
  43. Hsu JC (1996) Multiple comparisons theory and methods. Chapman & Hall, LondonCrossRefGoogle Scholar
  44. Kales S, Soteriades E, Christophi C, Christiani D (2007) Emergency duties and deaths from heart disease among firefighters in the United States. N Engl J Med 356:1207–1215CrossRefGoogle Scholar
  45. Kern W, Dodt C, Born J, Fehm HL (1996) Changes in cortisol and growth hormone secretion during nocturnal sleep in the course of aging. J Gerontol Ser A Biol Sci Med Sci 51:3–9CrossRefGoogle Scholar
  46. Konishi M, Takahashi M, Endo N, Numao S, Takagi S, Miyashita M, Midorikawa T, Suzuki K, Sakamoto S (2013) Effects of sleep deprivation on autonomic and endocrine functions throughout the day and on exercise tolerance in the evening. J Sports Sci 31:248–255. doi: 10.1080/02640414.2012.733824 CrossRefGoogle Scholar
  47. Leproult R, Copinschi G, Buxton O, Van Cauter E (1997) Sleep loss results in an elevation of cortisol levels the next evening. Sleep 20:865–870Google Scholar
  48. Lippi G, Franchini M, Salvagno G, Montagnana M, Guidi G (2008) Higher morning serum cortisol level predicts increased fibrinogen but not shortened APTT. J Thromb Thrombolysis 26:103–105CrossRefGoogle Scholar
  49. Lovallo WR, Whitsett TL, Al’Absi M, Sung BH, Vincent AS, Wilson MF (2005) Caffeine stimulation of cortisol secretion across the waking hours in relation to caffeine intake levels. Psychosom Med 67:734–739CrossRefGoogle Scholar
  50. Lovallo WR, Farag NH, Vincent AS, Thomas TL, Wilson MF (2006) Cortisol responses to mental stress, exercise, and meals following caffeine intake in men and women. Pharmacol Biochem Behav 83:441–447CrossRefGoogle Scholar
  51. Lundberg U (2008) Catecholamines and Environmental Stress. In: Allostatic Load notebook. Department of Psychology and Centre for Health Equity Studies (CHESS), Stockholm University. http://www.macses.ucsf.edu/research/allostatic/catecholamine.php#assessment
  52. Lundeland B, Gundersen Y, Opstad P-K, Thrane I, Zhang Y, Olaussen RW, Vaagenes P (2012) One week of multifactorial high-stress military ranger training affects Gram-negative signalling. Scand J Clin Lab Invest 72:547–554. doi: 10.3109/00365513.2012.705017 CrossRefGoogle Scholar
  53. Mackin P, Young AH (2004) The role of cortisol and depression: exploring new opportunities for treatments. Psychiatric Times 21:92–95Google Scholar
  54. Matthews K, Schwartz J, Cohen S, Seeman T (2006) Diurnal cortisol decline is related to coronary calcification: CARDIA study. Psychosom Med 68:657–661CrossRefGoogle Scholar
  55. McEwen B (1998) Stress, adaptation, and disease—allostasis and allostatic load. Ann N Y Acad Sci 840:33–44CrossRefGoogle Scholar
  56. McEwen B, Seeman T (1999) Protective and damaging effects of mediators of stress. Elaborating and testing the concepts of allostasis and allostatic load. Ann N Y Acad Sci 896:30–47CrossRefGoogle Scholar
  57. Meier-Ewert HK, Ridker PM, Rifai N, Regan MM, Price NJ, Dinges DF, Mullington JM (2004) Effect of sleep loss on C-reactive protein, an inflammatory marker of cardiovascular risk. J Am Coll Cardiol 43(4):678–683CrossRefGoogle Scholar
  58. Miller GE, Chen E, Zhou ES (2007) If it goes up, must it come down? Chronic stress and the hypothalamic-pituitary-adrenocortical axis in humans. Psychol Bull 133:25–45CrossRefGoogle Scholar
  59. Myles WS (1987) Self-paced work in sleep deprived subjects. Ergonomics 30:1175–1184CrossRefGoogle Scholar
  60. National Health and Medical Research Council (2013) Eat for health—Australian Dietary Guidelines. In: Australian Government, Department of Health and Ageing (ed). Canberra, AustraliaGoogle Scholar
  61. Neylan TC (2008) Intensity and physiological strain of competitive ultra-endurance exercise in humans. J Sports Sci 26:477–489CrossRefGoogle Scholar
  62. Neylan TC, Metzler TJ, Best SR, Weiss DS, Fagan JA, Liberman A, Rogers C, Vedantham K, Brunet A, Lipsey TL, Marmar CR (2002) Critical incident exposure and sleep quality in police officers. Psychosom Med 64:345–352CrossRefGoogle Scholar
  63. Nicolson NA (2008) Measurement of cortisol. In: Luecken LJ, Gallo LC, Luecken LJ, Gallo LC (eds) Handbook of physiological research methods in health psychology. Sage Publications Inc., Thousand Oaks, pp 37–74CrossRefGoogle Scholar
  64. O’Leary ÉD (2014) Effects of acute sleep restriction on laboratory and ambulatory physiological reactivity in young adults. In: NUI Galway Theses 2014-01-07T16:16:36ZGoogle Scholar
  65. Opstad P (1994) Circadian rhythm of hormones is extinguished during prolonged physical stress, sleep and energy deficiency in young men. Eur J Endocrinol 131:56–66CrossRefGoogle Scholar
  66. Opstad P, Aakvaag A (1981) The effect of a high calory diet on hormonal changes in young men during prolonged physical strain and sleep deprivation. Eur J Appl Physiol 46:31–39CrossRefGoogle Scholar
  67. Payne R, Welham S, Harding S (2011) A guide to REML in GenStat (16th ed), VSN International, Hemel HempsteadGoogle Scholar
  68. Peeters F, Berkhof J, Delespaul P, Rottenberg J, Nicolson NA (2006) Diurnal mood variation in major depressive disorder. Emotion 6:383–391. doi: 10.1037/1528-3542.6.3.383 CrossRefGoogle Scholar
  69. Pejovic S, Basta M, Vgontzas AN, Kritikou I, Shaffer ML, Tsaoussoglou M, Stiffler D, Stefanakis Z, Bixler EO, Chrousos GP (2013) Effects of recovery sleep after one work week of mild sleep restriction on interleukin-6 and cortisol secretion and daytime sleepiness and performance. Am J Physiol Endocrinol Metab 305:890–896CrossRefGoogle Scholar
  70. Perroni F, Tessitore A, Cibelli G, Lupo C, D’Artibale E, Cortis C, Cignitti L, Rosas MD, Capranica L (2009) Effects of simulated firefighting on the responses of salivary cortisol, alpha-amylase and psychological variables. Ergonomics 52:484–491CrossRefGoogle Scholar
  71. Phillips M, Netto K, Payne W, Nichols D, Lord C, Brooksbank N, Onus K, Jefferies S, Aisbett B (2011) Frequency, intensity and duration of physical tasks performed by Australian rural firefighters during bushfire suppression. Paper presented at the Australasian Fire Authorities/Bushfire Co-Operative Research Center Annual Conference, SydneyGoogle Scholar
  72. Phillips M, Payne W, Lord C, Netto K, Nichols D, Aisbett B (2012) Identification of physically demanding tasks performed during bushfire suppression by Australian rural firefighters. Appl Ergon 43:435–441. doi: 10.1016/j.apergo.2011.06.018 CrossRefGoogle Scholar
  73. Phillips M, Payne W, Netto K, Cramer S, Nichols D, McConell G, Lord C, Aisbett B (2015) Oxygen uptake and heart rate during simulated wildfire suppression tasks performed by Australian rural firefighters. Medical Sciences Accepted for PublicationGoogle Scholar
  74. Piazza JR, Charles ST, Stawski RS, Almeida DM (2013) Age and the association between negative affective states and diurnal cortisol. Psychol Aging 28:47–56. doi: 10.1037/a0029983 CrossRefGoogle Scholar
  75. Prodam F, Ricotti R, Agarla V, Parlamento S, Genoni G, Balossini C, Walker GE, Aimaretti G, Bona G, Bellone S (2013) High-end normal adrenocorticotropic hormone and cortisol levels are associated with specific cardiovascular risk factors in pediatric obesity: a cross-sectional study. BMC Med 11:1–11. doi: 10.1186/1741-7015-11-44 CrossRefGoogle Scholar
  76. Pruessner J, Kirschbaum C, Meinlschmid G, Hellhammer D (2003) Two formulas for computation of the area under the curve represent measures of total hormone concentration versus time-dependent change. Psychoneuroendocrinology 28:916–931. doi: 10.1016/s0306-4530(02)00108-7 CrossRefGoogle Scholar
  77. Reynolds A, Dorrian J, Liu P, Van Dongen H, Wittert G, Harmer L, Banks S (2012) Impact of five nights of sleep restriction on glucose metabolism, leptin and testosterone in young adult men. PLoS One 7:1–10. doi: 10.1371/journal.pone.0041218 Google Scholar
  78. Rodríguez-Marroyo JA, López-Satue J, Pernía R, Carballo B, García-López J, Foster C, Villa JG (2012) Physiological work demands of Spanish wildland firefighters during wildfire suppression. Int Arch Occup Environ Health 85:221–228. doi: 10.1007/s00420-011-0661-4 CrossRefGoogle Scholar
  79. Rosmond R, Wallerius S, Wanger P, Martin L, Holm C, Bjӧrntorp P (2003) A 5-year follow-up study of disease incidence in men with an abnormal hormone pattern. J Intern Med 254:386–390CrossRefGoogle Scholar
  80. Ruby B, Shriver T, Zderic T, Sharkey B, Burks C, Tysk S (2002) Total energy expenditure during arduous wildfire suppression. Med Sci Sports Exerc 34:1048–1054CrossRefGoogle Scholar
  81. Samel A, Vejvoda M, Maass H (2004) Sleep deficit and stress hormones in helicopter pilots on 7-day duty for emergency medical services. Aviat Space Environ Med 75:935–940Google Scholar
  82. Scott J, McNaughton L (2004) Sleep deprivation, energy expenditure and cardiorespiratory function. Int J Sports Med 25:421–426CrossRefGoogle Scholar
  83. Silverman MN, Sternberg EM (2012) Glucocorticoid regulation of inflammation and its functional correlates: from HPA axis to glucocorticoid receptor dysfunction. Ann N Y Acad Sci 1261:55–63. doi: 10.1111/j.1749-6632.2012.06633.x CrossRefGoogle Scholar
  84. Smith D, Petruzzello S, Chludzinski M, Reed J, Woods J (2005) Selected hormonal and immunological responses to strenuous live-fire firefighting drills. Ergonomics 48:55–65CrossRefGoogle Scholar
  85. Sparrow WA, Hughes KM, Russell AP, Le Rossignol PF (1999) Effects of practice and preferred rate on perceived exertion, metabolic variables and movement control. Hum Mov Sci 18:137–153CrossRefGoogle Scholar
  86. Spiegel K, Leproult R, Van Cauter E (1999) Impact of sleep debt on metabolic and endocrine function. Lancet 354:1435–1439CrossRefGoogle Scholar
  87. Spies K, Hesse F, Hummitzsch C (1996) Mood and capacity in Baddeley’s model of human memory. Zeitschrift für Psychologie mit Zeitschrift für angewandte Psychologie 204:367–381Google Scholar
  88. Steptoe A, Gibson EL, Hamer M, Wardle J (2007) Neuroendocrine and cardiovascular correlates of positive affect measured by ecological momentary assessment and by questionnaire. Psychoneuroendocrinology 32:56–64. doi: 10.1016/j.psyneuen.2006.10.001 CrossRefGoogle Scholar
  89. Tanskanen MM, Kyrolainen H, Uusitalo AL, Huovinen J, Nissila J, Kinnunen H, Atalay M, Hakkinen K (2011) Serum sex hormone-binding globulin and cortisol concentrations are associated with overreaching during strenuous military training. J Strength Cond Res 25:787–797. doi: 10.1519/JSC.0b013e3181c1fa5d CrossRefGoogle Scholar
  90. Taylor MK, Reis JP, Sausen KP, Padilla GA, Markham AE, Potterat EG, Drummond SPA (2008) Trait anxiety and salivary cortisol during free living and military stress. Aviat Space Environ Med 79:129–135CrossRefGoogle Scholar
  91. Thyfault JP, Carper MJ, Richmond SR, Hulver MW, Potteiger JA (2004) Effects of liquid carbohydrate ingestion on markers of anabolism following high-intensity resistance exercise. J Strength Cond Res (Allen Press Publishing Services Inc.) 18:174–179Google Scholar
  92. Tsigos C, Chrousos GP (2002) Hypothalamic–pituitary–adrenal axis, neuroendocrine factors and stress. J Psychosom Res 53:865–871. doi: 10.1016/S0022-3999(02)00429-4 CrossRefGoogle Scholar
  93. United States Fire Administration, National Fire Programs, National Fallen Firefighters Foundation (2014) Firefighter fatalities in the United States in 2013Google Scholar
  94. Van Cauter E, Spiegel K, Tasali E, Leproult R (2008) Original article: metabolic consequences of sleep and sleep loss. Sleep Med 9:S23–S28. doi: 10.1016/S1389-9457(08)70013-3 CrossRefGoogle Scholar
  95. van Leeuwen WMA, Lehto M, Karisola P, Lindholm H, Luukkonen R, Sallinen M, Härmä M, Porkka-Heiskanen T, Alenius H (2009) Sleep restriction increases the risk of developing cardiovascular diseases by augmenting proinflammatory responses through IL-17 and CRP. PLoS One 4:1–7. doi: 10.1371/journal.pone.0004589 CrossRefGoogle Scholar
  96. Verbyla AP, Cullis BR, Kenward MG, Welham SJ (1999) The analysis of designed experiments and longitudinal data by using smoothing splines. Appl Stat 48:269–311Google Scholar
  97. Vgontzas A, Mastorakos G, Bixler E, Kales A, Gold P, Chrousos G (1999) Sleep deprivation effects on the activity of the hypothalamic-pituitary-adrenal and growth axes: potential clinical implications. Clin Endocrinol 51:205–215CrossRefGoogle Scholar
  98. Vincent G, Ferguson S, Larsen B, Wolkow A, Tran J, Aisbett B (2015) Sleep restriction during simulated wildfire suppression: effect on physical task performance. PLoS One 10:1–16. doi: 10.1371/journal.pone.0115329.eCollection Google Scholar
  99. Weinkove C (1991) ACP broadsheet no 127: April 1991. Measurement of catecholamines and their metabolites in urine. J Clin Pathol 44:269–275CrossRefGoogle Scholar
  100. Westermann J, Demir A, Herbst V (2004) Determination of cortisol in saliva and serum by a luminescence-enhanced enzyme immunoassay. Clin Lab 50:11–24Google Scholar
  101. Willerson JT, Ridker PM (2004) Inflammation as a cardiovascular risk factor. Circulation 109:2–10. doi: 10.1161/01.cir.0000129535.04194.38 CrossRefGoogle Scholar
  102. Wolkow A, Netto K, Langridge P, Green J, Nichols D, Sergeant M, Aisbett B (2014) Coronary heart disease risk in volunteer firefighters in Victoria, Australia. Arch Environ Occup Health 69:112–120CrossRefGoogle Scholar
  103. Wolkow A, Aisbett B, Ferguson S, Main L (2015) The effects of work-related sleep restriction on acute physiological and psychological stress responses and their interactions: a review among emergency service personnel. Int J Occup Med Environ Health 28:183–208Google Scholar
  104. Wu H, Zhao Z, Stone WS, Huang L, Zhuang J, He B, Zhang P, Li Y (2008) Effects of sleep restriction periods on serum cortisol levels in healthy men. Brain Res Bull 77:241–245. doi: 10.1016/j.brainresbull.2008.07.013 CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Alexander Wolkow
    • 1
    • 2
    Email author
  • Brad Aisbett
    • 1
    • 2
  • John Reynolds
    • 4
  • Sally A. Ferguson
    • 2
    • 3
  • Luana C. Main
    • 1
  1. 1.Centre for Physical Activity and Nutrition Research (C-PAN)Deakin UniversityBurwoodAustralia
  2. 2.Bushfire Co-Operative Research CentreEast MelbourneAustralia
  3. 3.Appleton InstituteCQUniversityWayvilleAustralia
  4. 4.Biostatistics Unit, Faculty of HealthDeakin UniversityBurwoodAustralia

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