Executive functioning and working memory differences between insomnia patients and normally sleeping persons

Abstract

Background: Insomnia patients often report cognitive impairment. Diagnostic criteria for insomnia also imply the presence of neuropsychological deficits. Research, however, remains equivocal regarding this matter. The objective of this study was to investigate neuropsychological functioning in insomnia. Methods: Thirty-six participants diagnosed with insomnia were closely matched for gender, age, years of education, and ethnicity to a control group of 36 normally sleeping community contacts. All participants completed a valid, reliable and standardized insomnia questionnaire and a neuropsychological testing battery, which included measures of executive functioning (WCST, color-word and trails subtests of the DKEFS) and working memory (Letter Number Sequencing and Digit Span subtests of the WAIS-IV). Findings: Results pointed toward a mild executive functioning and working memory deficit in insomnia patients. Discussion: Results can be interpreted within the framework of “compensatory effort†and increased “mental loadâ€. Tasks of increased “mental load†may be more suitable for revealing cognitive difficulties in insomnia. Clinical implications include establishing more refined diagnostic criteria for insomnia and offering appropriate treatment for patients in high-risk occupations, where impairment may lead to accidents and lower work productivity.