Anti-dreaming device

The anti-dreaming device or sleep induction box (AUDIO: The Cradle of the Snake) or dream inhibitor (PROSE: The Dreaming) was a contraption devised by the Fifth Doctor that when worn, cancelled out the brainwaves associated with dreaming. The Doctor had Tegan wear it to stop her dreaming of the Mara. (TV: Snakedance)

The Eleventh Doctor later developed several dream inhibitors to keep the Mara's control from worsening over its victims. (PROSE: The Dreaming)