Chronic sleep curtailment impairs the flexible implementation of task goals in new parents.

Chronic sleep curtailment is a major concern for health in Western societies. Yet, research on potential consequences of long-term sleep curtailment on cognitive functions is still scarce. The present study investigated the link between chronic sleep limitation and executive functions that enable adaptation to changing environmental demands, i.e. the ability to flexibly implement task goals. To address the effects of chronic sleep restriction under real-life conditions, we considered a sample of adults who often suffer from reduced sleep durations over many months. One-hundred and six new parents (infant's age: 6-18months) were assigned to a sleep-curtailed group (<7h of nighttime sleep) and a non-sleep-curtailed group (≥7h of nighttime sleep), respectively, based on their self-reported average nighttime sleep duration over the preceding 6months. The ability to implement task goals was addressed applying a task-switching paradigm in which participants randomly switched between two tasks. While the two groups did not differ with regard to overall performance level, number of nighttime awakenings, naps during the day, daytime sleepiness, mood, chronic stress level and subjectively perceived cognitive capability, sleep-curtailed new parents showed higher costs for switching between tasks compared with repeating a task than non-sleep-curtailed new parents. This finding on the group level was further substantiated by a negative correlation between nighttime sleep duration and switch costs. With this study, we provide the first evidence for an impairment of the ability to flexibly implement task goals in chronically sleep-deprived new parents and, thus, for a link between chronic sleep curtailment and executive functions.