Technologies in the Film
In the beginning of the film, Emmet Brown brings Marty and Jennifer along to the future to fix the future of their children. Along the ride, Jennifer was asking too many questions about her future and the doc had to put her to sleep with "a sleep inducing alpha rhythm generator." This device instantly puts Jennifer to sleep for several hours, which becomes a problem later when the police find her. Similar devices have yet to exist, but there are several other ways of achieving the same effect.
Existing Technology and Patents
While several drugs already achieve effects of drowsiness or sleepiness, these kinds of sleep inducers are prevalent and easily obtainable. These drugs do not achieve the same effect as quickly. Other types of technology claim to slowly induce sleep through the use of ambient lights, comfortable sound blocking pillow helmets, and acupuncture techniques . These techniques are the current commercially available solutions for inducing sleep, but these do not work quite as rapidly as Doc Brown's handheld. There is one patent however, registered in 2006, that appears to be much like the doc's invention, featuring the same idea of an alpha rhythm machine to treat certain bodily problems, one of which is sleep disorders .
1. http://www.techradar.com/us/news/portable-devices... (26/4/2014)