Fatigue and its longitudinal associations with mood, stress, anxiety, and hair cortisol during the lockdowns of the COVID-19 pandemic: a cohort study with ecological momentary assessment

Objectives: The COVID-19 pandemic resulted in high levels of fatigue, while affecting individuals differently. This study aimed at identifying risk factors of experiencing fatigue during the first and second lockdown during the COVID-19 pandemic. The study also aimed at predicting fatigue, stress, anxiety, and mood dynamics during the second lockdown based on fatigue during the first lockdown. Finally, the study explores the link between hair cortisol and fatigue during COVID-19.Methods: In this ecological momentary assessment (EMA) study, 292 participants (231 women; Mage = 35.3 years, SDage = 13.1) provided data on fatigue, stress, anxiety, and mood for two seven-day measurement periods (20,343 observations) during the two national lockdowns in Austria and Germany. 85 participants provided hair strands for the analysis of hair cortisol.Results: Using linear mixed models, fatigue was related to younger age, lower socioeconomic status, higher chronic stress, and higher loneliness across both lockdowns. In addition, higher fatigue during the first lockdown was related to worse mood, higher fatigue, higher stress, and higher anxiety during the second lockdown. Finally, lower hair cortisol levels were related to a steeper diurnal increase in fatigue during the first lockdown.Conclusions: Risk factors for experiencing fatigue during the lockdowns of the COVID-19 pandemic were young age, low socioeconomic status, higher chronic stress, and higher loneliness. The results further suggest hypocortisolism of fatigued individuals in the general population during COVID-19. Identifying fatigued individuals early during crises could help inform appropriate intervention strategies for those most at risk.