Sleep & Recovery

How Space Travel Disrupts Sleep and Circadian Rhythms to Harm Heart and Brain

This review examines how the extreme environment of deep space — including microgravity, ionizing radiation, circadian rhythm disruption, and sleep disturbance — can alter heart and brain function in astronauts. The authors synthesize evidence from spaceflight observations, spaceflight experiments, and ground-based analog studies to identify shared biological mechanisms, including mitochondrial dysfunction, oxidative stress, metabolic disturbances, autonomic nervous system dysregulation, and inflammatory responses. While direct causal proof in astronauts remains limited, the findings have broad implications beyond space travel. The same mechanisms — circadian misalignment and chronic poor sleep — are increasingly recognized as drivers of cardiovascular and neurological aging on Earth, making this research relevant to anyone seeking to understand how sleep disruption harms long-term health.