Preliminary evidence of the cognitive cost of insomnia: understanding adaptive decision-making during sleep...

The aim of this laboratory-based study was to understand the effect of total sleep deprivation (TSD) on decision-making using a reversal learning task with unannounced contingency reversals in those with chronic insomnia compared to healthy sleepers.

Twenty-eight individuals completed the study, 15 with chronic insomnia (7 underwent TSD) and 13 healthy sleepers (7 underwent TSD). Participants were in the laboratory for 5 days/4 nights. Following baseline sleep, participants underwent 38 h of TSD or another nighttime sleep opportunity, followed by a recovery sleep opportunity for all participants. Mixed-effects ANOVAs with fixed effects of condition (healthy TSD, insomnia TSD, healthy control, or insomnia control), session (baseline or TSD/control), phase (pre or post-reversal), block (1-4), and their interactions were run to assess performance.

There were significant effects of day, condition, phase, and their interaction (all p<.01). Participants performed better when rested and pre-reversal (i.e. before the rule change). While both TSD groups showed poorer performance post-reversal (i.e. after the rule change) during TSD, the TSD insomnia group showed relatively intact performance pre-reversal.

TSD led to significant overall impairment on a reversal learning decision task for healthy sleepers and those with insomnia. However, the nature of impairment differed between groups. Hyperarousal may have conferred a protective effect on those with insomnia, resulting in preserved decision-making pre-reversal. These findings have important implications for our understanding of the nature of cognitive impairment associated with chronic insomnia.