Question of the Study In insomnia, sleep problems negatively affect patients' daytime functioning. Thus, the aim of this study was to assess the deterioration of the noopsyche (i. e. intellectual and mnestic performance) and thymopsyche (i. e. drive, mood, affectivity, wakefulness) in sleep laboratory-investigated patients with nonorganic insomnia (ICD-10: F51.0) as compared with healthy controls in midmorning hours. Patients and Methods 179 patients (93 females, 86 males; aged between 22 and 63 years) divided into eight diagnostic subgroups (one group without and seven groups with concomitant psychiatric disorders) were noopsychically compared with age-and sex-matched healthy controls in regard to intelligence (Lehrl's Mehrfachwahl Wortschatz Test), visual memory (Benton Test), verbal memory (Gruenberger Verbal Memory Test) and psychomotor activity (Gruenberger Fine Motor Test). In regard to the thymopsyche, drive, mood, affectivity and wakefulness were evaluated by means of visual analogue scales, well-being was evaluated by the Von Zerssen mood scale, and state and trait anxiety were assessed by the Spielberger State/Trait Anxiety Inventory. Results Regarding noopsychic performance, crystallized intelligence was not decreased in insomniac patients. Visual memory revealed an increase in reproduction errors in all patient groups. In insomnia associated with affective disorders, total verbal memory and psychomotor activity showed a deterioration, while in nonorganic insomnia without concomitant psychiatric disorder and insomnia related to generalized anxiety disorder or adjustment disorders, no deterioration was found for these variables. Regarding the thymopsyche, wakefulness was impaired in all patient groups. Daytime drive, mood, affectivity, well-being and anxiety showed a marked deterioration in insomniacs due to affective disorders, but not in patients with nonorganic insomnia without concomitant psychiatric disorder or insomnia related to generalized anxiety disorder or adjustment disorders. Conclusion In conclusion, daytime dysfunction ± an important criterion in the ICD-10 definition of insomnia ± is indeed a frequently observed and objectifiable phenomenon, with the quantity and quality of noopsychic and thymopsychic dysfunction dependent on the concomitant psychiatric disorder.