Could Sleep Be an Antidote to Optic Disc Edema in Astronauts?

A spectrum of neuro-ocular changes has been observed in astronauts during and after prolonged exposure to microgravity on long-duration spaceflights. These changes, collectively referred to as "spaceflight associated neuro-ocular syndrome" (SANS), pose a significant challenge for space agencies as they prepare for future human missions, including a return to the Moon and manned missions to Mars. Optic disc edema, a hallmark feature of SANS, occurs in approximately 70% of astronauts on extended missions. Recent evidence suggests a potential link between poor sleep and the development of optic disc edema in individuals exposed to a spaceflight analog environment, providing critical insights into its underlying pathophysiology. Here, we propose a novel hypothesis: sleep deprivation may increase the risk of microgravity-induced optic disc edema by altering translaminar pressure dynamics and disrupting ocular glymphatic outflow. This perspective offers a new framework for understanding SANS and highlights potential targets to mitigate its risks in the context of human space exploration.