 This process results in their body undergoing a transformation, gaining a new physical form and a new personality; a Time Lord who was pleasant and polite in his previous regeneration might express surprise when his new form turns out to be prone to saying rude things.Regenerations can be traumatic.In "Castrovalva", the Fifth Doctor requires the use of a Zero Room, a chamber shielded from the outside universe that provides an area of calm for him to recuperate.