Association of table salt use with sleep patterns and depressive symptoms: population-based analysis with external clinical replication.

Background: Dietary habits are modifiable factors related to sleep health, yet the association between discretionary table-salt use and sleep patterns-and the potential role of depressive symptoms-remains incompletely understood. We investigated the association between table-salt use and sleep patterns and assessed whether depressive symptoms may statistically account for part of this association. Methods: This dual-cohort study integrated a nationally representative analysis of 8,440 adults from the National Health and Nutrition Examination Survey (NHANES, 2005-2010) with an independent external clinical replication cohort of 488 patients from Gansu Provincial People's Hospital. The exposure was the frequency of adding salt at the table, and the outcome was an unhealthy sleep pattern (a composite score derived from sleep duration, trouble sleeping, and diagnosed sleep disorder). Mediation analyses were performed to quantify the indirect association component via depressive symptoms (PHQ-9). Results: In NHANES, frequent table salt use was independently associated with higher odds of unhealthy sleep patterns compared with rare/occasional use (OR = 1.27, 95% CI: 1.11-1.46; Conclusion: More frequent discretionary table salt use was associated with unhealthy sleep patterns in a nationally representative sample, with directionally consistent findings in an external clinical replication cohort. Depressive symptoms statistically accounted for a substantial proportion of the observed association. Given the cross-sectional design, temporality cannot be established, and mediation results should be interpreted as a statistical decomposition of associations rather than causal mediation. Prospective studies with repeated measurements and intervention trials are needed to test temporal ordering and causal mechanisms.