Does Suspected Sleep Disordered Breathing Impact on the Sleep and Performance of Firefighting Volunteers during a Simulated Fire Ground Campaign?

Abstract

Adequate sleep is fundamental to workplace performance. For volunteer firefighters who work in safety critical roles, poor performance at work can be life threatening. Extended shifts and sleeping conditions negatively impact sleep during multi-day fire suppression campaigns. Having sleep disordered breathing (SDB) could contribute further to sleep deficits. Our aim was to investigate whether those with suspected SDB slept and performed more poorly during a fire ground simulation involving sleep restriction. Participants, n = 20 participated in a 3-day-4-night fire ground simulation. Based on oximetry desaturation index data collected during their participation, participants were retrospectively allocated to either a SDB (n = 8) or a non-SDB group (n = 12). The simulation began with an 8 h Baseline sleep (BL) followed by two nights of restricted (4 h) sleep and an 8 h recovery sleep (R). All sleeps were recorded using a standard electroencephalography (EEG) montage as well as oxygen saturation. During the day, participants completed neurobehavioral (response time, lapses and subjective fatigue) tasks. Mixed effects ANOVA were used to compare differences in sleep and wake variables. Analyses revealed a main effect of group for Total sleep (TST), REM , wake after sleep onset (WASO) and Arousals/h with the SDB group obtaining less TST and REM and greater WASO and Arousals/h. The group × night interaction was significant for N3 with the SDB group obtaining 42 min less during BL. There was a significant main effect of day for RRT, lapses and subjective fatigue and a significant day × group interaction for RRT. Overall, the SDB group slept less, experienced more disturbed sleep and had poorer response time performance, which was exacerbated by the second night of sleep restriction. This could present a safety concern, particularly during longer campaigns and is worthy of further investigation. In addition, we would recommend promotion of awareness of SDB, its symptoms and potential impact among volunteers and relevant agencies.

Keywords: fatigue; firefighters; obstructive sleep apnea; performance; sleep; sleep disordered breathing.

Figure 1

Sleep Variables. Mean ± Standard error or measurement (SEM) for TST, Efficiency, Arousals/h, WASO, N3, REM, SOL, Subjective Sleep Quality for the two groups: SDB, non-SDB and across the 4-nights: Baseline (BL), Experimental Night 1 (E1), Experimental Night 2 (E2) and Recovery (R).

Figure 2

Wake Variables. Mean ± Standard error or measurement (SEM) for (top panel to bottom panel): Response time (reciprocal transformation used, RRT and scale inverted). Lapses (Response Times >500 ms) and Subjective Fatigue Ratings across the 3-days: Baseline, Experimental Day 1 (E1), Experimental Day 2 (E2) and across Time: 0930/1030, 1400, 1600, 1800. * Denotes significant difference compared to Baseline Day; ** Denotes significant difference compared to Experimental Day 1.