Astronaut shows how they sleep in space

What if we told you that you can 'completely relax' without sleeping on a mattress with a pillow?

The only catch - you'll need to be an astronaut to know what it feels like.

Watch below as Chris Hadfield of the Canadian Space Agency shows us how it's done:

Chatting to us from the International Space Station, Hadfield says that the on-board sleeping arrangements need to be 'comfortable for the astronauts'.

Sleeping in space also allows the body to 'completely relax' because since there's no gravity, 'you don't need anything to hold you up', Hadfield explains.

"It's space, you don't even have to hold your head up," he explains.

"So you can relax every muscle in your body and your arms float up in front of you and you head tips forward."

That's why there's no need for a pillow or mattress. All you need a sleeping bag tied to the wall.

Canadian Space Agency/NASA

While showing off his 'comfy Russian full-length pyjamas' to the cameras, Hadfield takes us to his sleeping pod.

As shown in the clip above, it's basically a claustrophobic-looking white pod with a green sleeping bag attached upright to the wall.

The CSA say that sleeping upright makes no difference whatsoever and that the sleeping bag has a rigid cushion to elevate pressure on an astronaut's back.

The personal sleep compartments happen to be the size of a telephone booth, where astronauts are typically given a sleeping bag, a pillow, a lamp, an air vent, a personal laptop and a place for personal belongings.

Those on board also tend to use earplugs and a sleep mask to block out the noise and light, since this can make it difficult to get a good night's rest.

Canadian Space Agency/NASA

In a separate video shared back in 2013, Hadfield also showed us what happens when you cry in space.

He said that he's often asked what happens when you tear up in space - which is a bit surprising - so he decided to clear it up once and for all.

However, Hadfield said he can't cry on demand, so he squirted some water in his eye instead.

After wetting his eyeballs, the astronaut commented: "So, just as if I started crying, my eye's full of tears. But you can see it just forms a ball on my eye.

Canadian Space Agency/NASA

"In fact, I can put more water in. And so if you keep crying, you just ended up with a bigger and bigger ball of water in your eye, until eventually it crosses across your nose and gets into your other eye, or evaporates, or maybe spreads over your cheek - or, you grab a towel and dry it up.

"So yes, I've gotten things in my eye, your eyes will definitely cry in space, but the big difference is tears don't fall."

The more you know.