Fatigue or excessive daytime sleepiness: which is more closely related to depression?

ABSTRACT

OBJECTIVE/BACKGROUND: This study investigated fatigue and excessive daytime sleepiness to determine which was more closely related to depression in the general population. PATIENTS/METHODS: Participants were investigated across 15 South Korean districts. Excessive daytime sleepiness, fatigue, and depression were evaluated using the Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), and Patient Health Questionnaire-9 (PHQ-9), respectively. Depression was defined as PHQ-9 ≥ 10. The authors classified the combination of excessive daytime sleepiness and fatigue as excessive daytime sleepiness with fatigue (E+F+, ESS ≥ 11, FSS ≥ 36), fatigue without excessive daytime sleepiness (E-F+, ESS < 11, FSS ≥ 36), excessive daytime sleepiness without fatigue (E+F-, ESS ≥ 11, FSS < 36), and no fatigue and excessive daytime sleepiness (E-F-, ESS < 11, FSS < 36). RESULTS: Among 2,493 participants (1,257 women), mean age was 47.9 ± 0.3 years. The prevalence of depression, fatigue, and excessive daytime sleepiness was 8.4% (n = 210), 30.8% (n = 767), and 15.3% (n = 382), respectively. The frequency of the four categories with depression (vs. controls) was as follows. E+F+ (n = 67, 31.9% vs. 7.3%) (P < 0.001), E-F+ (n = 71, 33.8% vs. 20.3%) (P < 0.001), E+F-( n = 16, 7.6% vs. 5.8%) (P = 0.294), and E-F- (n = 56, 26.7% vs. 66.6%) (P < 0.001). After adjusting for covariates, depression was associated with E+F+ (odds ratio, OR 8.804, 95% confidence interval (CI) 5.818-13.132), E-F+ (OR 3.942, 95% CI 2.704-5.747), E+F- (OR 2.812, 95% CI 1.542-5.131), and E-F- (reference). Additionally, we performed logistic regression according to two categories. There was no significant difference in the association of depression between E+F- (reference) and E-F+ (OR 1.399, 95% CI 0.760-2.575). CONCLUSION: Although fatigue and excessive daytime sleepiness were associated with depression regardless of the presence of each other, we could not clarify which was more closely related to depression.