Sleep better - Think better! - The effect of CBT-I and HT-I on sleep and subjective and objective neurocognitive performance in university students with insomnia

Cognitive demands placed on university students are high and so is the prevalence of insomnia in this population. Neurocognitive functions, such as delayed recall, working memory, and flexibility are often impaired in patients with insomnia disorder. Therefore, this study investigates the development of neuropsychological functioning in students with insomnia symptoms over the course of a sleep training. In this pilot-study 54 university students with symptoms of insomnia were included and randomly assigned to a group intervention with cognitive behavioural therapy and hypnotherapy (n = 35) and a waiting-list control condition (n = 19). Sleep quality and objective measures of neurocognitive performance (attention, inhibition, flexibility, memory, and working memory) were assessed before and after the training or a waiting period of 6 weeks. Both the intervention condition and the waiting-list control condition improved with regards to sleep quality, sleep duration, sleep efficiency, and measures of higher cognitive functions. In addition, students in the intervention condition reported less subjective daytime impairments when compared to the waiting-list control condition. The subgroup of students with short sleep duration benefitted significantly from the intervention in flexibility and working memory tasks. In line with previous studies, improved sleep was associated with improved neuropsychological functioning. The additional improvements observed in students with short sleep duration indicate an association between insomnia severity and neuropsychological improvement.