eHealth Literacy and Search Frequency in Relation to Objective Sleep Disorder Knowledge: Cross-Sectional Study.

Background: The increasing use of the internet for health information has made eHealth literacy a critical factor in health knowledge acquisition and management. While eHealth literacy has been associated with positive health behaviors and knowledge in various contexts, its impact on disease-specific knowledge, particularly for sleep disorders, remains limited. Objective: This study aimed to examine the relationship between eHealth literacy and search frequency with objective knowledge about sleep disorders, and test whether the frequency of health information searches moderates the association between eHealth literacy and knowledge. Methods: An online survey was conducted with 266 adult participants. eHealth literacy was measured using the revised eHealth Literacy Scale, and the frequency of health information searches was assessed using a single-item scale. Objective knowledge about sleep disorders was evaluated using a newly developed scale tailored for this study. Hierarchical regression analysis was conducted to examine the main effects of eHealth literacy and search frequency on sleep disorder knowledge, while controlling for demographic variables such as age, gender, education, and past experience with sleep disorders. The interaction effect between eHealth literacy and frequency of health information searches on sleep disorder knowledge was further assessed using the PROCESS macro (model 1) to explore moderation effects. Results: Higher eHealth literacy was positively associated with greater objective knowledge about sleep disorders (B=0.27, SE 0.06, P<.001). Search frequency also showed a significant positive association with knowledge (B=0.24, SE 0.06; P<.001). In addition, the interaction between eHealth literacy and search frequency was significant (B=-0.61, SE 0.27; P=.03). Specifically, the positive link between eHealth literacy and knowledge was the strongest among individuals who searched less frequently and weakened as search frequency increased, becoming nonsignificant at the highest observed level of search frequency. Conclusions: eHealth literacy and search frequency were both linked to greater knowledge of sleep disorders. However, the strength of the literacy-knowledge association differed across levels of search frequency. The relationship was stronger when search frequency was low and weaker among frequent seekers. These findings suggest that eHealth literacy and information-seeking behaviors jointly shape factual knowledge. Supporting eHealth literacy together with guidance on efficient information use may help patients acquire more accurate health knowledge. This study also introduces a newly developed scale for assessing objective knowledge about sleep disorders, providing a foundation for consistent evaluation of disease-specific knowledge.