The ink in the pen needs Gravity to push the ink out and write. As no gravity is present in Space, a special and different type of pen is made for astronauts filled with Nitrogen which pushes the ink out of it and helps in writing.
The astronauts are required to use the water effectively and efficiently in space as it is expensive and difficult to transport. Instead of Bathing, they take Sponge Bath.
In Space, the astronauts start losing their sense of taste and once back on earth the food tastes much stronger.
The ban of Alcohol in space is not a Scientific thing rather it is more of a Cultural and Political thing. But Russians are allowed Alcohol in space for Immune Health reasons.
The Astronauts witness at least 16 sunsets which disrupts their sleep cycle and confuses them when to sleep. They are given excessive training on sleeping too before they go to space.
Bread and Soda are banned in space as the breadcrumbs might float away and can damage the spaceship or can be accidentally inhaled by the astronauts.
Astronaut Chris Hadfield said that you cannot cry as the tears form into a Liquid Ball and stings in the eyes. The tears are not able to fall down due to loss of Gravity.