Associations of Self-Reported Temporomandibular Disorder Symptoms with Sleep Problems, Perceived Stress, and Alexithymia in Young Adults: A Cross-Sectional Study

Background: Temporomandibular disorders (TMDs) are increasingly understood as chronic pain conditions in which biological susceptibility and psychosocial factors interact. Alexithymia, a personality trait characterized by difficulty identifying and describing feelings, has been linked to chronic pain; however, its relationship with self-reported TMD symptoms, perceived stress, and sleep problems in non-clinical young adults remains insufficiently explored. Objective: To examine the associations of self-reported TMD symptom severity with sleep problems, perceived stress, and alexithymia in young adults. Methods: In this cross-sectional online survey, 634 participants aged 18–40 years (74.3% female) completed the Fonseca Anamnestic Index (FAI), the 20-item Toronto Alexithymia Scale (TAS-20), the 14-item Perceived Stress Scale (PSS-14), and the Jenkins Sleep Scale (JSS). Group comparisons, Spearman correlations, and hierarchical multiple linear regression with FAI score as the dependent variable were performed. All analyses were re-run on the raw data during revision. Results: Self-reported TMD symptoms of any severity were present in 90.5% of participants. FAI scores correlated weakly to moderately with JSS (r = 0.40), PSS-14 (r = 0.37), and TAS-20 (r = 0.29) scores (all p < 0.001). After adjustment for sociodemographic variables (R2 = 0.147), sleep problems (β = 0.24), perceived stress (β = 0.16), and alexithymia (β = 0.14) explained an additional 14.6% of the variance in FAI scores (final R2 = 0.292; p < 0.001). Female sex, older age within the 18–40 range, and residence in an earthquake-affected province were also independently associated with higher FAI scores. Among the alexithymia dimensions, only difficulty identifying feelings was independently associated with FAI scores. Conclusions: In this young adult sample, self-reported TMD symptom severity was associated with sleep problems, perceived stress, and alexithymia, with weak-to-moderate effect sizes. Given the cross-sectional design and reliance on self-report, these findings reflect associations only—causal or temporal relationships cannot be inferred, and the findings support considering psychosocial factors when TMD-related symptoms are assessed.