The human brain, which is suspended in clear cerebrospinal fluid inside the skull, can also be impacted by the effects of microgravity - in a surprisingly tangible way. As detailed in a new study published by an international team of researchers in the journal PNAS, the brain "shifts upward and backward within the skull following spaceflight, with sensory and motor regions exhibiting the largest shifts."
Ask any astronaut who has spent extended periods in the International Space Station what the most challenging part was, and they will probably say missing friends and family. While there are plenty of amazing and unique experiences, life in space comes with other little challenges, too - try getting your hair to stay flat without gravity or wearing the same outfit for days on end.