Cryosleep pods were devices that saw usage by the Chiss during 18 BBY, and by the Grysk around 2 BBY.
One such device was utilized by Mitth'raw'nuruodo, who held the rank of Senior Captain, to detain The Magys. This occurred after she commanded her companion to die and before she could end her own life following the events of the first skirmish over Sunrise. Mitth'ali'astov, a Caregiver, compared the look of the pods to coffins.
The Grysk race employed these chambers for the purpose of moving Force-sensitive Chiss females whom they had taken prisoner. During the battle of Mokivj, the Galactic Empire managed to retrieve these chambers.
The novel Thrawn: Alliances, released in 2018, marked the initial introduction of hibernation chambers.