Sleep stability and cognitive function in an Arctic Martian analogue.

INTRODUCTION

Human performance is affected by sleep disruption and sleep deprivation can critically affect mission outcome in both spaceflight and other extreme environments. In this study, the seven-person crew (four men, three women) lived a Martian sol (24.65 h) for 37 d during a long-term stay at the Flashline Mars Arctic Research Station (FMARS) on Devon Island, Canada. Crewmembers underwent cardiopulmonary monitoring for signs of circadian disruption and completed a modified Pittsburgh Sleep Diary to monitor subjective fatigue. Crewmembers underwent cognitive testing to identify the effects, if any, of sleep disruption upon cognitive skill.

METHODS

A Martian sol was implemented for 37 d during the Arctic mission. Each crewmember completed an adapted version of the Pittsburgh Sleep Diary in tandem with electrocardiograph (ECG) cardiopulmonary monitoring of sleep by the Cardiac Adapted Sleep Parameters Electrocardiogram Recorder (CASPER). Crewmembers also underwent cognitive testing during this time period.

RESULTS

Sleep diary data indicate improvement in alertness with the onset of the sol (fatigue decreasing from 5.1 to 4.0, alertness increasing from 6.1 to 7.0). Cardiopulmonary data suggest sleep instability, though trends were not statistically significant. Crewmember decision speed time scores improved from pre-Mars to Mars (average improving from 66.5 to 84.0%), though the remainder of cognitive testing results were not significant.

DISCUSSION

While subjective data demonstrate improved sleep and alertness during the sol, objective data demonstrate no significant alteration of sleep patterns. There was no apparent cognitive decline over the course of the mission.