Welcome back to Earth! After an unexpected nine-month stint aboard the International Space Station, astronauts Sunita ‘Suni’ Williams and Barry ‘Butch’ Wilmore are feeling the gravity of their journey—quite literally. 

What was supposed to be a brief eight-day mission extended into almost a year in microgravity, bringing with it a host of unique health challenges. Whether you’re a space enthusiast or just curious about the after-effects of floating among the stars, this exploration of astronaut health is truly out of this world.

Neurological Adjustments

Readapting to Earth’s gravity isn’t just a physical challenge—it’s a nerological one as well. After nine months of weightlessness aboard the International Space Station, astronauts Suni and Butch are undergoing significant neurological adjustments. This process involves reorienting their vestibular system, which is crucial for balance and spatial orientation.

• Space Motion Sickness: Upon their return, astronauts often experience what is known as space motion sickness. This condition is characterized by nausea, dizziness, and disorientation—symptoms that occur as the body struggles to recalibrate to Earth’s gravity. These symptoms can be intense initially but typically diminish over the first few days back on solid ground.
• Loss of Sense of Direction: In space, the lack of gravity means there’s no up or down, which can disrupt an astronaut’s sense of direction. After returning to Earth, the reintroduction of gravity forces their brains to adjust back to a world where direction matters, and this readjustment can take time.
• Vestibular Recalibration: The vestibular system, which includes parts of the inner ear and brain that help control balance and eye movements, undergoes significant changes during prolonged periods in microgravity. Upon return, astronauts must retrain their bodies to manage gravity. This recalibration is critical for performing everyday activities without experiencing disorientation or loss of balance.

Bone Density Loss

One of the most critical concerns for astronauts after prolonged exposure to microgravity is the loss of bone density. The environment of space, devoid of gravity, means that the bones do not bear the same loads they do on Earth, leading to a weakening of bone structure.

In microgravity, astronauts experience bone density loss at a rate similar to individuals who are bedridden on Earth. This rapid deterioration is especially prevalent in bones that typically bear weight, such as the spine, pelvis, and legs. Over the course of their nine-month mission, astronauts like Williams and Wilmore can lose up to 1% of their bone density each month.

The pelvis and the spine are particularly susceptible to bone density reductions. However, it’s the smaller, less weight-bearing bones, such as those in the forearm, that may take longer to recover once back on Earth. This delayed recovery can extend vulnerability to fractures and other bone-related injuries well after astronauts return.

Skin and Immune System Vulnerability

The challenges of returning to Earth from space extend beyond bones and brains. Astronauts like Suni and Butch also face unique vulnerabilities in their skin and immune systems, consequences of the harsh conditions of space travel.

• Skin Sensitivity and Health: The microgravity environment of space affects the skin’s ability to renew and protect itself. Astronauts often experience thinner, more sensitive skin after prolonged stays in space. This sensitivity is compounded by a decreased ability to repair small cuts, bruises, and rashes, making skin care a significant concern during and after missions.
• Immune System Suppression: Beyond skin health, the immune system also undergoes significant changes. Spaceflight conditions—such as radiation exposure, stress, and altered sleep cycles—contribute to a weakened immune response. This suppression makes astronauts more susceptible to infections during their stay in space and initially upon their return to Earth.
• Microbial Growth: The space station’s closed environment can also lead to changes in microbial growth on the skin and within the body. These microbes behave differently in space, sometimes becoming more aggressive, further complicating the health challenges astronauts face.

Radiation Exposure

Astronauts face significant risks from radiation exposure during their time in space, far beyond what we experience on Earth. The lack of Earth’s atmosphere and magnetic field in space allows for much higher levels of cosmic rays and solar radiation, presenting serious health risks.

In space, astronauts are exposed to approximately 100 times the radiation that people are exposed to on Earth. This exposure is continuous and comes from cosmic rays and solar particles, which can penetrate spacecraft walls and human tissue.

Immediate risks include radiation sickness, which can cause symptoms ranging from nausea and vomiting to more severe conditions depending on the exposure level. Long-term, astronauts face increased risks of cancer, cardiovascular disease, and other degenerative diseases such as cataracts and neurological disorders due to the damage radiation can cause to DNA and cellular structures.

One of the more concerning risks involves the potential impact on the central nervous system. Exposure to high levels of radiation can lead to cognitive declines, changes in motor function, and other neurological symptoms, which could be debilitating.

Muscle Atrophy

In the microgravity environment of space, the absence of gravity means that the body does not need to support its own weight, leading to decreased use of muscle groups that are typically engaged in weight-bearing activities on Earth. This results in the gradual weakening of muscle fibers, particularly in the legs, back, and core areas.

Upon return to Earth, astronauts often struggle with basic mobility tasks such as standing, walking, and climbing stairs. The loss of muscle strength can significantly affect their balance and coordination, increasing the risk of falls and injuries shortly after landing.

To combat muscle atrophy, astronauts adhere to rigorous exercise regimens while in space, involving two hours of cardiovascular and resistance training each day. These workouts are performed on specialized equipment designed to simulate the effects of weight-bearing exercises, such as treadmills with harness systems and resistance exercise devices.

Mental Health Concerns

The mental health of astronauts is an essential aspect of space travel that requires as much attention as physical health. Sunita Williams and Barry Wilmore, like many astronauts who spend extended periods in space, face unique psychological challenges both during their mission and upon their return to Earth.

Extended missions on the International Space Station (ISS) involve prolonged periods of isolation and confinement in a small space. This can lead to feelings of loneliness, depression, and anxiety. The psychological strain of being away from family and familiar social interactions is compounded by the stress of constant vigilance and work demands in a high-risk environment.

Many astronauts experience a profound shift in perspective known as the Overview Effect—seeing Earth from space can alter their sense of connection to the planet and humanity. While often described as a positive transformative experience, this realization can also lead to existential reflections and conflicts that might impact an astronaut’s mental well-being.

Upon returning to Earth, astronauts must readjust not only physically but also mentally. They might feel out of place or overwhelmed by the sudden return to normal life and the sensory overload of everyday Earth environments. This transition can trigger a range of emotions, from relief to sadness, and may require psychological support to manage.

My Personal RX: What We Can Learn From Astronauts About Brain Health

Astronauts face some of the most extreme conditions known to the human body—which don’t just affect physical health but they also have measurable impacts on brain structure, cognitive function, and emotional well-being. Studying how astronauts adapt offers us powerful insights into how stress, environmental changes, and lifestyle factors shape our own brain health here on Earth. The good news? Many of the protective strategies used in space can be applied in everyday life to help safeguard our cognitive and mental health.

1. Support Cognitive Function with Probiotics: MindBiotic offers a blend of probiotics, prebiotics, and adaptogens that supports the gut-brain axis. A healthy gut microbiome can improve mental clarity and mood stability, which is crucial in environments that challenge mental resilience.
2. Optimize Nutrition for Brain Health: Utilize the Healthy Gut Cookbook to prepare meals rich in nutrients that support brain function. Recipes packed with omega-3 fatty acids, antioxidants, and vitamins help maintain brain health and overall physical wellness.
3. Simulate Space Exercise Regimens: Regular physical activity is crucial, as demonstrated by astronauts’ daily routines to combat muscle and bone loss. On Earth, regular exercise promotes blood flow to the brain and may improve cognitive functions.
4. Adopt Structured Daily Routines: Astronauts follow strict schedules to manage life in space. Similarly, establishing regular sleep, exercise, and meal routines helps maintain circadian rhythms and supports cognitive health.
5. Engage in Cognitive Training Exercises: Just like astronauts train for mental tasks, you can engage in brain games, puzzles, or new learning activities to enhance mental agility and memory retention.
6. Prioritize Social Interaction: Isolation in space can impact mental health, similar to loneliness on Earth. Ensure regular, meaningful social interactions to improve mood and cognitive resilience.
7. Create a Low-Stress Environment: Just as astronauts must manage environmental stressors in space, it’s crucial to minimize stressors in our environments on Earth. Cultivate a peaceful home and workspace by reducing clutter, using calming colors in your decor, and incorporating plants, which can help reduce stress and improve air quality
8. Manage Stress with Mindfulness Techniques: Astronauts use various techniques to handle stress. Incorporate mindfulness practices such as meditation or yoga to reduce stress, which is essential for maintaining cognitive functions.
9. Stay Hydrated: Proper hydration is crucial for maintaining concentration and cognitive function. Emulate the careful water intake management of astronauts by ensuring you drink enough fluids throughout the day.
10. Ensure Quality Sleep: In space, maintaining a sleep schedule is key for performance. On Earth, 7-9 hours of quality sleep per night supports neuroplasticity and cognitive processing.