Individual Differences in Response to Sleep Deprivation in a Space Analog Environment

Abstract

Adverse conditions in space severely affect astronauts' sleep. Importantly, previous research yielded evidence that even minor sleep deprivation has the potential to massively influence individual performance. Thus, considering the high risk operational working environment of space missions, it is essential to study potential influences on the effects of sleep deprivation. As part of a larger NASA project, our study aimed at investigating whether individual characteristics such as personality traits predict vulnerability to sleep deprivation with respect to individuals' performance and perceived fatigue. The study was conducted in the NASA Human Exploration Research Analog (HERA), a ground-based habitat. Data were collected from four four-person crews, who volunteered to partake in confined isolation for 45 days each. Before participating, individual characteristics such as personality traits were assessed. During confinement, the crew members were instructed to maintain a sleep rhythm of eight hours per night during weekends and five hours per night during weekdays (i.e., inducing sleep deprivation). Moreover, repeatedly during the mission, participants' performance was measured by means of the psychomotor vigilance task (PVT) and, additionally, several rating scales were administered (e.g., perceived fatigue). In contrast to prior research, extraversion did not predict differential impairment in PVT performance or perceived fatigue as a result of sleep deprivation in the present study. However, we found several other individual characteristics such as the personality trait aggressiveness to be significantly associated with vulnerability to the effects of sleep deprivation. In addition to our main analyses, we also explored the time courses of three basic dimensions of mood during the mission (i.e., valence, calmness, energetic arousal). In sum, the present study made use of an ecologically valid space analog to shed further light on the relationship between individual characteristics such as personality traits and vulnerability to the effects of sleep deprivation.