The patient was given a powerful 'sedative'.
the 'sedative' effects of the drug
(..) collapse with the slightest disturbance. Sedation. For sleep stable enough to create three layers of dreaming... ...we'll have to combine it with an extremely powerful sedative. Good night. YUSUF: The compound we'll be using to share the dream... ...creates a clear connection between dreamers... (..)2010 Inception
(..) A dream within a dream? Two levels? Three. Not possible. That many dreams within dreams is too unstable. It is possible. You just have to add a sedative. A powerful sedative. - How many team members? - Five. SAITO: Six. The only way to know you have done the job (..)2010 Inception