OBJECTIVES: Airline cabin crew experience high levels of fatigue and sleepiness. Whether these are solely related to their work schedules/jetlag or are in part related to individual factors is unknown. The COVID-19 pandemic has significantly disrupted the aviation industry and many cabin crew have been grounded. This provides a unique opportunity to assess the causes of fatigue and sleepiness in this population.METHODS: An online anonymous survey was distributed in April–June 2020 to cabin crew who were 1) flying, 2) grounded but doing alternative work, and 3) grounded, not working, or unemployed. The survey measured fatigue, sleepiness, and mental health. It also screened their risk for insomnia, depression, and shift work disorder and assessed drug and caffeine use.RESULTS: Collected were 409 valid responses: 45 currently flying; 35 grounded but doing alternate work; and 329 not working. On average, all three groups experienced normal levels of fatigue and sleepiness. The risk for major depressive disorder was 27.4%, with 59.5% of individuals reporting abnormal levels of anxiety. Caffeine intake and the use of drugs and alcohol to facilitate sleep were common, although not different between those currently flying vs. grounded.CONCLUSIONS: With reduced workloads or not flying, cabin crew reported lowered fatigue and sleepiness compared to prepandemic findings, along with reduced risk for major depressive disorder. However, a high occurrence of negative emotional states were reported, potentially related to the uncertainty surrounding the pandemic. This study suggests fatigue and sleepiness is primarily related to airline operational rather than personal variables.Wen CC-Y, Nicholas CL, Howard ME, Trinder J, Jordan AS. Understanding sleepiness and fatigue in cabin crew using COVID-19 to dissociate causative factors. Aerosp Med Hum Perform. 2022; 93(1):50–53.