Why do astronauts grow taller in space? 

Want to grow taller? Book a ticket to the space. Though this is a rather impossible proposition, the science behind it cannot be ignored. Do you know that the astronauts who visit the international space station for a prolonged time come back taller? That’s amazing, isn’t it?  Let’s explore what happens to our bodies in space.  

How can space make you tall?  
So let’s understand how astronauts gain height while in space.  You know that the astronauts or space scientists visit the International Space Station (ISS) in space and stay onboard for many months to conduct their research and experiments. Now, ISS, being in space has microgravity (zero gravity) and as it orbits our planet, astronauts experience the microgravity and the feeling of weightlessness too.  Scientists say, staying in the environment of heightened radiation and microgravity for long periods of time can result in changes in the human body. And one of these changes is that it makes you taller. The question is how and why.  

So, each of the discs in our spine is separated by cartilage, a tough yet flexible tissue found in the body. While we are on Earth, gravitational force compresses the spine. But when in the microgravity environment of space, the cushion-like cartilage doesn’t feel the same compression force. So, the vertebrae can expand and relax, elongating the spine and therefore, increasing the height.   

How much taller do astronauts get? You can say, the body can grow in height by up to 3 per cent. So, if an astronaut is 6 feet tall, he can grow up to 2 inches.  

Is it a permanent gain?  
No, this is only for some time. When astronauts return to the Earth they face the same gravity due to which the spine once again becomes compressed. Over time, they return to their previous  height. 

Gravity affects our height outside space too! 
Interestingly, we experience something very similar with our bodies in our day-to-day lives. When you go to sleep at night lying horizontally, the spine doesn’t experience the vertical pull of gravity that it does when you’re moving around throughout the day. So, you’ll find that you’re probably one centimetre taller when you wake up in the morning compared to when you lie down at night.  

Life in space and its side effects 
It seems all fun to gain a few inches. After all who doesn’t like to be taller? But it has its own side effects too. Around 50 per cent of astronauts, after returning to Earth, face back pain issues which have been correlated with spinal unloading (transition from gravity to zero gravity).  

Also, due to zero gravity, their bones become weak as they can lose some bone mass every month they spend in space. Fluids in their body shift upward because of the lack of gravity and can cause puffiness. That’s why the kind of food, medicine, and exercise regimen astronauts follow are so important. The presence of cosmic radiation also raises the risk of cancer and damage to the nervous system.