Tidal breathing was a relaxation techniques taught to the Jedi Padawan Barriss Offee by her master Luminara Unduli. By concentrating on exhaling deeply, relaxing and drawing a deep breath, then repeating the actions, a Jedi could shed mental burdens and reach a deeper, more receptive state of mind. This allowed them to make an intense connection to the Force, becoming a conduit for it's power.