Venegas Joshua M, Rosenberg Mark
Department of Aerospace & Human Performance, The Medical University of South Carolina, 171 Ashley Ave, Charleston, SC 29425, United States.
Department of Aerospace & Human Performance, The Medical University of South Carolina, 171 Ashley Ave, Charleston, SC 29425, United States.
Life Sci Space Res (Amst). 2025 Aug;46:39-42. doi: 10.1016/j.lssr.2025.03.009. Epub 2025 Apr 1.
A unique constellation of ocular structural changes and visual anomalies known as Spaceflight Associated Neuro-ocular Syndrome (SANS) affects 70 % of crew members after long-duration spaceflight. Current hypotheses regarding the etiology of SANS discuss cephalad fluid shifts and venous congestion, which are correlated with elevated intra-cranial pressure (ICP) and enlarged perivascular spaces (PVS). These PVS comprise the glymphatic system (GS), a recently discovered network of influx and efflux pathways for cerebrospinal fluid (CSF) and metabolites in the central nervous system (CNS). Both glymphatic clearance and traditionally understood CSF circulation are affected by sleep-wake cycles, displaying a significant increase in fluid flow during sleep. Natural sleep has been associated with a 60 % increase in interstitial space in animal studies, which likely enhances GS exchange and outflow. Corresponding studies in humans using contrast-enhanced MRI associate sleep with greater glymphatic clearance compared to wakefulness. The sleep problems of astronauts during long-duration spaceflight have been well documented, ranging from sleep disruption and decreased quality to insufficient sleep duration. With recent terrestrial studies providing evidence that sleep deprivation impairs molecular clearance from the human brain, it follows that similar glymphatic dysfunction may arise due to these conditions in astronauts. Thus, in addition to impairing crew member work performance on long-duration space missions, sleep deprivation may exert long-term neuro-ocular effects via decreased glymphatic efficiency and clearance. The adverse impact of the resulting cognitive and visual disturbances presents a major future performance risk to astronauts. This work discusses the existing body of literature regarding the connections between circadian disruption and glymphatic disruption as a potential contributing mechanism for the development of SANS. This association should receive focused attention in future research as a potential risk factor for SANS. In addition, interventions that enhance extraterrestrial sleep quality and duration may prove to be practical countermeasures for the prevention of this syndrome.
一种独特的眼部结构变化和视觉异常组合，被称为航天相关神经眼科综合征（SANS），会影响70%的长期太空飞行机组人员。目前关于SANS病因的假说讨论了头向体液转移和静脉充血，这与颅内压（ICP）升高和血管周围间隙（PVS）扩大相关。这些PVS构成了类淋巴系统（GS），这是一个最近发现的中枢神经系统（CNS）中脑脊液（CSF）和代谢物的流入和流出途径网络。类淋巴清除和传统理解的脑脊液循环都受睡眠-觉醒周期影响，在睡眠期间液流显著增加。在动物研究中，自然睡眠与间质空间增加60%相关，这可能会增强GS交换和流出。在人类中使用对比增强MRI的相应研究表明，与清醒相比，睡眠时类淋巴清除更多。长期太空飞行期间宇航员的睡眠问题已得到充分记录，从睡眠中断、质量下降到睡眠时间不足。最近的地面研究提供证据表明，睡眠剥夺会损害人脑中的分子清除，因此宇航员在这些情况下可能会出现类似的类淋巴功能障碍。因此，除了损害长期太空任务中机组人员的工作表现外，睡眠剥夺可能会通过降低类淋巴效率和清除率产生长期神经眼科影响。由此产生的认知和视觉干扰的不利影响对宇航员未来的表现构成了重大风险。这项工作讨论了关于昼夜节律紊乱和类淋巴紊乱之间联系的现有文献，这是SANS发展的一个潜在促成机制。这种关联作为SANS的一个潜在风险因素，应在未来研究中得到重点关注。此外，提高外星睡眠质量和持续时间的干预措施可能被证明是预防该综合征的切实对策。
