Doc, at the wheel of the DeLorean time machine, puts Jennifer to sleep.

" Doc leaned over, holding a silver, penlight-sized device in front of Jennifer's face. The penlight-thing strobed a blue light in Jennifer's eyes. / Jennifer slumped in her seat, sound asleep. / "Doc!" Marty objected. "What are you doing?" / "Relax, Marty," Doc Brown reassured him. "It's just a sleep-inducing alpha rhythm generator. She was asking too many questions. No one should know too much about their future." Doc glanced at her again. Jennifer snored softly. "This way, when she wakes up, she'll think it was all a dream." "
—From Back to the Future Part II by Craig Shaw Gardner (quote, page 16)

The sleep-inducing alpha rhythm generator, was a device invented sometime before 2015 used to help induce sleep.


Dr. Emmett Brown used an alpha rhythm generator on Marty McFly's girlfriend Jennifer Parker to prevent her from remembering the events of time travel.

Doc also used the device on Marty's future son, Marty Jr., so that Marty — wearing a color-shifting lenticular baseball cap and auto-adjusting jacket — could take his place at a meeting with Griff Tannen at the Cafe 80's.

However, because of its recent use on Jennifer, the device did not have enough power to knock Marty Jr. out for a full hour as Doc had wanted. As a result, Marty Jr. still arrived at the cafe where Marty was pretending to be his own son to confront Griff.


  • Doc also refers to the device as simply "the sleep inducer".

Behind the scenes[]

  • The device that Doc demonstrated apparently had two lights that would shine into a person's eyes and send a signal similar to the brain wave pattern shown during the early stages of sleep.
  • As others have pointed out [1], this is not one of Doc's inventions, but an "EZ Sleep" product that he purchased.


  • Patents have been granted for alpha rhythm generators, though not for anything resembling the device used by Doc in Back to the Future Part II. Most recently, patent #7,155,285 was issued in 2006 by the United States Patent Office[2] for an "apparatus for inducing energies of alpha rhythm to the human body".


See also[]


  1. Back to the Future Part II at Tripod.com (see 'External links' below)
  2. PatentStorm - U.S. Patents Library and Database (see 'External links' below)

External links[]