British astronaut Tim Peake discovered what causes the "world's worst hangover" and that's the journey from the International Space Station (ISS) back to Earth after spending six months in space. The homebound astronauts endured a three-hour flight inside a cramped space capsule, the bumpy re-entry conditions and of course, the rough landing in Kazakhstan on June 18.

Along with Tim Peake, NASA astronaut Tim Kopra and Roscosmos cosmonaut Yuri Malenchenko arrived on Earth on June 18 aboard a parachuted Soyuz spacecraft. The trio spent 186 days in space.

A Russian recovery team on the landing site retrieved the astronauts. They were immediately transferred to reclining seats and flown to their respective bases. After their much-needed readjustment period, Tim Peake faced the media again to share their out-of-this-world experiences in a press conference. When asked if Peake would like to return to space, he was quoted saying he will "in a heartbeat."

Major Peake added that adjusting to the Earth's gravity is harder than he had expected and that the apparent change to his physical appearance is a shock to the British astronaut and former pilot. "It's a bit slower coming the other way, I can tell you, and it's a bit harder. You look at yourself and the mirror, and think 'wow.' I'm only 2kg off my launch weight. But It's really easy to see that your frame is different," ESA astronaut Tim Peake, said in a press conference.

But aside from that, he expressed his interest to be chosen for future space flights including ESA's upcoming lunar mission. He also shared that he was amazed at how fast the human body can adapt to new environments saying that he was able to function well within 24 hours on the ISS.

But spending six months in microgravity is expected to incur an unexpected effect to the human body.

"You're excited to be back, but you can't fully enjoy the experience because, to be quite frank, you feel pretty terrible," Peake said in an interview published by Science Alert. "It can only be described as something akin to the world's worst hangover in terms of the everything that is going on in your head," added Peake.

To help the astronauts recover from the now dubbed world's worst hangover, Peake specifically will undergo strict exercise regime and medical tests including MRI, blood tests and psychological evaluations. And as per his job as an astronaut, ESA said his work is far from over. His body, as well as the others that went home with him from the ISS, will provide crucial data in understanding how the human form adapts, survives and changes during long-duration space missions.