Suspended animation, sometimes called cryo-storage was first used by the Gielians on their sleeper ships.

They first tried to share their sleeper ship technology with the Razudans, but their cryo-technology proved to be incompatible with Razudan biology. Eventually, a process was discovered to freeze the Mammalian Humans, Malev, and Aryss (actually it was by partially, but temporarily, changing the circulatory systems of their bodies to more insect-like systems). The Aryss have, for the most part, objected to the process, calling the procedure an abhorrence.

Though the processes were discovered to freeze many races, it's not used very often in space travel, because the discovery of other forms of interstellar space travel have mostly made the technology obsolete, and the process is very expensive in materials and energy. The rich who travel a lot tend to use it while traveling to extend lifespan. The equipment is standard on most Ultima Corporation corporate travel ships.

The process has been used to preserve live in the case of patients who would be otherwise terminally ill, while medical technology catches up to illnesses. The energy costs aren't nearly as prohibitive on planets, and the material costs are either cheap enough to afford, or the costs can be mostly offset by government subsidies if you can't afford it yourself. But those are only in the cases where additional time will save the patient (i.e. a disease without a current cure).