COGPITStudy: COGnitive Function, Performance and Irregular Timing of Sleep –An epidemiology and mathematical modeling approach–

• Applicant: Dr. Dorothee Fischer
• Subject Area: Epidemiology and Medical Biometry/Statistics ; Public Health, Healthcare Research, Social and Occupational Medicine
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439835894

The alternation of sleep and wakefulness is regulated by two processes: a homeostatic and a circadian process that interact so that sleep is consolidated at night. Shift work requires workers to be active at times when the body is prepared to rest, resulting in insufficient sleep, delayed sleep onset, and irregular day-to-day sleep. While adverse effects of short and mistimed sleep (i.e., during the day) are by now well-documented, a recent systematic review on irregular sleep concluded that “this body of literature is still at its infancy”. Irregular sleep often occurs in response to irregular work schedules (e.g., shift work), posing a risk to worker’s health and safety. Safety is a major concern in aviation, where lapses of attention are potentially fatal. Although some studies have examined the effect of irregular sleep on cognitive performance, none have been conducted in the aviation sector and all of them used 'traditional' metrics for quantifying irregular sleep. These traditional metrics –such as Standard Deviation (StDev) and Inter-daily Stability (IS)– quantify overall variability in sleep (e.g., averaging across many days), rather than quantifying the degree to which sleep patterns differ between consecutive days. Two recent (‘2nd-generation’) metrics have been developed to specifically capture day-to-day changes in sleep patterns: the Composite Phase Deviation (CPD) metric and the Sleep Regularity Index (SRI). Using CPD and SRI, the proposed project combines approaches in epidemiology and mathematical modeling to examine potential adverse effects of irregular sleep on cognitive function and identify shift schedules that reduce irregular sleep and improve cognitive performance. In Objectives I–III, I will use three epidemiological datasets from the “Hispanic Community Health Study” (n1=16,415, n2=2,252, n3=6,378) to (I) quantify exposure to irregular sleep calculating traditional (StDev, IS) and 2nd-generation (CPD, SRI) metrics, (II) estimate cross-sectional and prospective associations of irregular sleep with cognitive function, and III) compare predictive power among traditional and 2nd-generation metrics. In Objectives IV–VI, I will apply an adenosine-based mathematical model of sleep-wake regulation and cognitive performance to three datasets in commercial aviation (n1=31, n2=24, n3=381) to (IV) evaluate the predictive accuracy of the mathematical model in the target population of pilots and cabin crew members, V) associate predicted increased fatigue and impaired cognition with flight schedule characteristics, and VI) simulate alternative flight schedules to improve predicted sleep and cognitive performance. The proposed project will help determine the role of irregular sleep for cognitive function in addition to sleep duration and timing and identify potential interventions to optimize sleep and cognitive performance on flight rosters in aviation.

• DFG Programme: Research Grants