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Updated: Jun 14, 2025

Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments
Published on: August 8, 2019
Daily variation in sleepiness among firefighters while working the 24/48 and 48/96 shift schedules
Joel M Billings1, Sara A Jahnke2, Christopher K Haddock2
1Department of Security and Emergency Services, Embry-Riddle Aeronautical University, Daytona Beach, FL, United States.
Objective:
To assess the daily relationship between prior-night total sleep time (TST) and next-day, afternoon sleep propensity among firefighters operating from two popular fire department shift schedules.
Methods:
Dataset included 22 firefighters (24/48 shift schedule) and 20 firefighters (48/96 shift schedule). Daily TST was assessed using actigraphy and daily sleep propensity was assessed using the Epworth Sleepiness Scale (ESS), completed every afternoon.
Results:
Separate one-way repeated measures ANOVA indicated statistically significant differences among daily sleep propensity within each shift schedule. Separate Pearson product moment correlations indicated moderate relationships between prior-night TST and next-day, afternoon sleep propensity.
Conclusion:
When firefighters slept less, sleep propensity the following day increased. Least TSTs occurred on nights prior to commuting suggesting firefighters likely begin shifts without sufficient sleep and drive home without sufficient sleep, then experience greatest sleep propensity.
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