Verbal fluency difficulties in Chinese insomnia patients: insights from semantic and phonemic tasks

Insomnia is a prevalent sleep disorder associated with cognitive difficulties, including reduced performance in executive control and semantic memory. This study explores the impact of insomnia on language retrieval processes using the Chinese Verbal Fluency Test (VFT), addressing the need for cognitive research beyond English-speaking populations. We hypothesised that insomnia-related difficulties in semantic memory and executive control would result in reduced VFT performance. Participants with insomnia (N=20) and matched healthy controls (N=20) were recruited from a community outpatient clinic in China to complete an online Chinese VFT, generating words for semantic categories (e.g., animals) and phonemic conditions (e.g., words beginning with "bai" [, "white"]). Compared with controls, the insomnia group produced fewer correct responses across both tasks; the between-group gap was larger for semantic correct responses. Clustering and switching analyses showed fewer switches in the semantic task for the insomnia group and a reduced phonemic mean cluster size, suggesting difficulties in executive control processes. Together, these convergent results indicate reduced efficiency in both semantic memory retrieval and control-guided search during word production. By employing a Chinese VFT and parallel semantic and phonemic tasks, the study extends current evidence beyond alphabetic languages and highlights how language-specific demands can shape fluency performance. Overall, the findings clarify how sleep disturbances may influence core components of language processing and support the value of process-level fluency measures in characterising cognitive difficulties linked to insomnia.