Your intelligence and constitution both increase by one

Gallifreyans speak common

Darkvision 60 ft

as a Gallifreyan you do not sleep like most other races and are immune to exhaustion

as a Gallifreyan you are extremely difficult to kill, so when you fail three death saving throws instead of dying you regenerate and roll a new appearance from the below charts. You stay unconscious but regain full hit points. For 24 hours after your regeneration you are extremely weak and if you drop below zero hit points you die instantly without rolling anything.

gallifreyans age at a much slower rate than most other races