Sleep debt and outside employment patterns in helicopter air medical staff working 24-hour shifts.

INTRODUCTION: Twenty-four hour availability creates physiological and psychological challenges for air medical teams. The 24-hour shift (24H) is a common staffing pattern in the air medical community. We report sleep dept and pre-duty activity patterns for 24H medical staff members at helicopter air medical transport programs.
METHODS: An anonymous survey collecting self-reported sleep quantities for off-duty, immediate pre-duty, and on-duty periods, along with self-reported outside employment patterns, was distributed to medical team members at cluster sample of 10 rotor wing air medical programs selected by stratified random sample to ensure geographic and operational diversity. Both matched-sample comparisons of sleep quantities in different phases of the duty-cycle and independent-sample comparisons between staff with and without outside employment had 80% power to detect a difference in means of 60 minutes at a 0.05 two-sided significance level using the appropriate t-test. Descriptive statistics are also reported; means are reported with the standard deviation.
RESULTS: A total of 138 surveys were returned (69.0%) and the 133 (66.5%) that were fully completed were utilized for analysis. 24H crewmembers average nearly the same amount of sleep in 24 hour periods on both duty and non-duty days (6.9 +/- 1.3 v. 6.4 +/- 1.8 hours, p = NS, range 3 - 10 for duty days and 4 - 10 for non-duty days). On duty, they average 1.1 +/- 1.3 hours of sleep in the first half of their shifts (range 0 to 5) and 5.3 +/- 1.4 hours in the overnight portion (range 2 - 9). The lowest amount of on-duty sleep reported in the past 30 days ranged from 0 to 6 hours, averaging 1.9 +/- 1.7 hours. The minimum pre-duty sleep reported by 24H crewmembers prior to any shift in the past month averaged 4.6 +/- 1.6 hours (range 0-8), with 3.8% having reported in the past month with no sleep before their 24-hour shift. Outside employment (OE) in addition to the flight position was common for 24H crewmembers (81.1% of respondents). Pre-duty sleep did not differ significantly between 24H crewmembers with and without OE, but 16.3% of surveyed 24H crewmembers with OE had reported for flight duty within eight hours of leaving OE within the past 30 days.
CONCLUSION: In the programs surveyed, 24H crewmembers completed an average duty cycle with little sleep debt and were unlikely to be sleepless prior to reporting for a shift. OE is common for 24H medical staff and some personnel report for flight duty within eight hours of leaving an OE position. As the industry considers the impact of fatigue on operational safety, shift length, on-duty rest, and outside employment will be important considerations.