title: Acute Psychophysiological Relationships Between Mood, Inflammatory and Cortisol Changes in Response to Simulated Physical Firefighting Work and Sleep Restriction.
abstract: This study examined how changes in wildland firefighters' mood relate to cytokine and cortisol levels in response to simulated physical firefighting work and sleep restriction. Firefighters completed 3 days of simulated wildfire suppression work separated by an 8-h (control condition; n = 18) or 4-h sleep opportunity (sleep restriction condition; n = 17) each night. Firefighters' mood was assessed daily using the Mood Scale II and Samn-Perelli fatigue scale. Participants also provided samples for the determination of salivary cortisol and pro- (IL-6, IL-8, IL-1β, TNF-α) and anti-inflammatory (IL-4, IL-10) cytokine levels. An increase in the positive mood dimension Happiness was related to a rise in IL-8 and TNF-α in the sleep restriction condition. A rise in the positive mood dimension Activation among sleep restricted firefighters was also related to higher IL-6 levels. An increase in the negative mood dimension Fatigue in the sleep restriction condition was associated with increased IL-6, TNF-α, IL-10 and cortisol levels. In addition, an increase in Fear among sleep restricted firefighters was associated with a rise in TNF-α. Elevated positive mood and immune activation may reflect an appropriate response by the firefighters to these stressors. To further understand this relationship, subsequent firefighting-based research is needed that investigates whether immune changes are a function of affective arousal linked to the expression of positive moods. Positive associations between negative mood and inflammatory and cortisol levels to physical work and restricted sleep provide useful information to fire agencies about subjective fire-ground indicators of physiological changes.
authors.affiliation: Centre for Physical Activity and Nutrition Research, Deakin University, 221 Burwood Hwy, Burwood, VIC, 3125, Australia. awolkow@deakin.edu.au.|Bushfire Co-Operative Research Centre, East Melbourne, 3002, Australia. awolkow@deakin.edu.au.
authors.forename: Alexander
authors.initials: A
authors.lastname: Wolkow
authors.affiliation: Centre for Physical Activity and Nutrition Research, Deakin University, 221 Burwood Hwy, Burwood, VIC, 3125, Australia.|Bushfire Co-Operative Research Centre, East Melbourne, 3002, Australia.
authors.forename: Brad
authors.initials: B
authors.lastname: Aisbett
authors.affiliation: Biostatistics Unit, Faculty of Health, Deakin University, Burwood, 3125, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Reynolds
authors.affiliation: Bushfire Co-Operative Research Centre, East Melbourne, 3002, Australia.|Appleton Institute, Central Queensland University, Wayville, 5034, Australia.
authors.forename: Sally A
authors.initials: SA
authors.lastname: Ferguson
authors.affiliation: Centre for Physical Activity and Nutrition Research, Deakin University, 221 Burwood Hwy, Burwood, VIC, 3125, Australia.
authors.forename: Luana C
authors.initials: LC
authors.lastname: Main
mesh_terms: D061388:Firefighters; D006801:Humans; D006854:Hydrocortisone; D016753:Interleukin-10; D012890:Sleep; D012892:Sleep Deprivation
chemical_list: D016753:Interleukin-10; D006854:Hydrocortisone
keywords: Cortisol; Cytokines; Fatigue; Mood; Physical work; Sleep restriction