Nonlinear Association of Daily Sitting Time With Depression Risk in US Adults: A Cross‐Sectional Study

BACKGROUND: Previous studies have examined the relationship between daily sitting time and depression, yet the specific dose-response relationship remains unclear. METHODS: This study analyzed data from 29,691 participants in the 2007-2018 National Health and Nutrition Examination Survey (NHANES). To delve into the possible nonlinear link between daily sitting time and depression, smooth curve fitting and threshold effect analysis were utilized in the study. Information on daily sitting time was collected through questionnaires, and the Patient Health Questionnaire-9 (PHQ-9) was employed to measure depression. RESULTS: In the fully adjusted Model 3, each additional hour of sitting was associated with a 5% increase in the risk of depression (95% CI: 1.02, 1.07, p = 0.0002). When categorizing daily sitting time, participants who sat for 8 h or more daily exhibited a significantly higher risk of depression across all models. In Model 3, this group had an odds ratio (OR) of 1.37 (95% CI: 1.12, 1.69, p = 0.0039) compared with the reference group sitting for less than 4 h. The threshold effect analysis identified 7 h as the inflection point. Below this threshold, no significant correlation was observed. In contrast, when daily sitting time exceeded the threshold, there was a significant increase in the risk of depression, with an OR of 1.07 (95% CI: 1.01, 1.12, p = 0.0184). CONCLUSIONS: A nonlinear association exists between daily sitting time and depression risk in US adults. However, additional research is required to further validate this finding.