Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments.

Sleep loss and circadian misalignment contribute to a meaningful proportion of operational accidents and incidents. Countermeasures and work scheduling designs aimed at mitigating fatigue are typically evaluated in controlled laboratory environments, but the effectiveness of translating such strategies to operational environments can be challenging to assess. This manuscript summarizes an approach for collecting sleep, circadian, fatigue, and performance data in a complex operational environment. We studied 44 airline pilots over 34 days while they flew a fixed schedule, which included a baseline data collection with 5 days of mid-morning flights, four early flights, four high-workload mid-day flights, and four late flights that landed after midnight. Each work block was separated by 3-4 days of rest. To assess sleep, participants wore a wrist-worn research-validated activity monitor continuously and completed daily sleep diaries. To assess the circadian phase, pilots were asked to collect all urine produced in four or eight hourly bins during the 24 h after each duty block for the assessment of 6-sulfatoxymelatonin (aMT6s), which is a biomarker of the circadian rhythm. To assess subjective fatigue and objective performance, participants were provided with a touch-screen device used to complete the Samn-Perelli Fatigue Scale and Psychomotor Vigilance Task (PVT) during and after each flight, and at waketime, mid-day, and bedtime. Using these methods, it was found that sleep duration was reduced during early starts and late finishes relative to baseline. Circadian phase shifted according to duty schedule, but there was a wide range in the aMT6s peak between individuals on each schedule. PVT performance was worse on the early, high-workload, and late schedules relative to baseline. Overall, the combination of these methods was practical and effective for assessing the influence of sleep loss and circadian phase on fatigue and performance in a complex operational environment.

Validation of a touchscreen psychomotor vigilance task.

OBJECTIVE: The purpose of this study was to compare a psychomotor vigilance task developed for use on touchscreen devices with the original PVT-192 in conditions of acute sleep loss and circadian desynchronization. BACKGROUND: The Psychomotor Vigilance Task (PVT) is considered the gold standard fatigue detection test and is used frequently in fatigue research. With the rapid development of new technologies it is essential to develop a PVT available on different platforms such as touchscreen devices. The advantage of such PVT is that it can be implemented on small devices and can be easily used in field studies. METHODS: Ten participants completed a 5-min PVT (NASA-PVT) on a touchscreen device and a 5-min PVT on the original PVT-192. On the day of the experiment, participants arrived in the lab approximately two hours after their habitual wake time. Participants completed a constant routine protocol under dim lighting, while maintaining a constant posture. The 5-min PVT-192 and NASA-PVT were taken every two hours for at least 24h. RESULTS: The NASA-PVT and PVT-192 were sensitive to extended wakefulness in the same manner. The reaction times were slower and the lapses were higher as time progressed on both NASA-PVT and PVT-192 (p<0.001). Overall, there was a sharp decline in performance after 16h of being awake which coincided with the time the participants were usually going to bed and the worst performance occurred after 24h of wakefulness for both PVTs (p<0.001). CONCLUSIONS: Overall, our data suggest that the NASA-PVT is a valid tool for assessing fatigue in field studies.