Neurocognitive performance in insomnia disorder: The impact of hyperarousal and short sleep duration

Given the recent evidence on the association between hyperarousal in insomnia disorder and neurocognitive deficits, we aimed to examine the effect of short sleep duration on neurocognitive reaction time tests in insomnia disorder sufferers. We recruited subjects with insomnia disorder (n = 35, mean age = 40.6 years) who scored >= 29 on a Hyperarousal Scale, and a group of controls (n = 54, mean age = 31.5 years) who had no sleep disorders and scored <26 on the Hyperarousal Scale. Participants completed two in-home polysomnograms and four daytime trials of neurocognitive tests, including simple reaction time, choice reaction time, big circle-little circle, rapid visual information processing, attention switching task, and spatial working memory tests. Total sleep time divided study cohorts into subgroups of short (total sleep time <6 hr) and normal (total sleep time >= 6 hr) sleepers. ANCOVA showed a significant interaction between participant type (insomnia disorder versus controls) and sleep duration (short versus normal) for spatial working memory-latency (p = 0.020) and spatial working memory-errors (p = 0.025). The short-sleeping insomnia disorder group had longer spatial working memory-latencies and more spatial working memory-errors than did normal-sleeping controls. Regardless of sleep duration, those with insomnia disorder had more attentional deficits with longer attention switching task-latency (p = 0.011) and more attention switching task-incorrect trials (p = 0.015) than the control group. Normal-sleepers only had longer attention switching task-latency than short-sleepers (p = 0.004). A phenotype of insomnia disorder with hyperarousal and short sleep duration is associated with daytime cognitive deficits in complex attentional and spatial working memory tasks.