Differences in total sleep time and heart rate variability between shift types in firefighters.

Area of Science:

• Occupational Health
• Sleep Science
• Cardiovascular Physiology

Background:

• Firefighting is a demanding occupation with irregular work schedules.
• Understanding physiological responses to shift work is crucial for firefighter well-being.
• Heart Rate Variability (HRV) and readiness scores are key indicators of physiological state.

Purpose of the Study:

• To compare total sleep time and HRV in active-duty firefighters on shift versus off shift.
• To investigate the relationship between sleep patterns and physiological readiness in firefighters.

Main Methods:

• A longitudinal observational study involving 59 structural firefighters over 15 weeks.
• Smart ring technology was used to collect nightly sleep data and calculate readiness scores.
• Data were analyzed comparing on-shift and off-shift days.

Main Results:

• Firefighters obtained more total sleep time on off-shift days (6.97 hours) compared to on-shift days (6.68 hours).
• Heart Rate Variability (HRV) and readiness scores were significantly lower on off-shift days.
• Total sleep time showed a moderate positive correlation with the subsequent day's readiness score.

Conclusions:

• While firefighters sleep longer when off-shift, their HRV and readiness are higher when on-shift.
• Sleep duration is associated with readiness and HRV, but these physiological systems are complex.
• These findings highlight the intricate interplay between sleep, HRV, and readiness in the firefighting profession.