When Astronauts are in space their  cartilage disc in the spine expands due to the absence of gravity.
But gradually after they reach earth their height returns to normal.Without the presence of gravity the  the spines are able to relax.The suits worn by astronauts in space stations must have room to accommodate  the change in height.
This change in height up to 2 inches.
This phenomenon has a similarity in some terms to what happen when we sleep at night,because when we lie down gravity is not pushing down our vertebrae. But the change in height is small  compared to what happens to astronauts in space.