Relationship between subjective and objective fatigue and sleep characteristics in individuals with anxiety and mood disorders: An exploratory study

Objective: Fatigue and sleep disturbances are important symptoms of anxiety and mood disorders (AMD). Studies about the relationship between these variables usually rely on self-report assessments. Therefore, the aim of our exploratory study was to investigate the independent correlations between subjective and objective fatigue and sleep characteristics in individuals with AMD.Methods: In sum, 233 individuals with AMD attending a stress-related disorders day care unit (78.5 % females, mean age 39.0 years old) participated in a cross-sectional study. Participants completed the Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, Multidimensional Fatigue Inventory-20, and Pittsburgh Sleep Quality Index self-report questionnaires, as well as an exercise capacity workload test for assessing objective fatigue and polysomnography monitoring for evaluation of sleep structure.Results: In individuals with AMD, exercise capacity workload was associated with lower percent of stage 1 sleep (8 = -0.17, p = 0.006), REM latency (8 =-0.13, p = 0.042), and wake after sleep onset (8 =-0.12, p = 0.039). General fatigue was associated with a higher percent of body movements (8 = 0.12, p = 0.047), as well as mental fatigue was associated with a higher percent of body movements (8 = 0.13, p = 0.029), and a higher score on the PSQI (8 = 0.21, p = 0.002). Conclusions: Objective sleep characteristics were associated with objective assessment of fatigue, while subjective sleep quality was associated with subjectively assessed mental fatigue.