The first commonly-recognized use of the term 'Sightings' in the media was the successful 1990s tv series of the same name.

Sightings is an American paranormal documentary and news television series that originally aired from April 17, 1992 to August 1, 1997. The program began as a special titled The UFO Report: Sightings on October 18, 1991. The original Concept Creator and Supervising Producer of that hour special produced by Paramount for Fox TV was Linda Moulton Howe, an Emmy Award-winning TV producer and documentary filmmaker of TV specials about science and the environment. One of her Emmy award-winning broadcasts was A Strange Harvest (KMGH-TV in May 1980), about the worldwide animal-mutilation mystery linked by law enforcement to extraterrestrial biological entities.

After the special broadcast to high ratings, it went forward into weekly TV production as the series Sightings. The show featured everything from UFOs to ghosts to Bigfoot in an investigative news format and was hosted by reporter Tim White. The show was created by Ann Daniels Productions, Fair Dinkum Productions, and Paramount Domestic Television. One of its executive producers was Henry Winkler.

The series began on Fox in 1992 (the first Paramount Television production ever to air on that network), in a 30-minute long format that aired on Friday nights. When the show was put into syndication in 1994, it was extended to an hour long format and was on at various times. In 1996, it was picked up by Sci Fi Channel. Sightings was cancelled in 1997 (although five special episodes aired in 1998), and reruns continued on the Sci Fi Channel until April 2003.

In 2002, one of the stories featured on Sightings became the subject of a television movie, called Sightings: Heartland Ghost. The movie tells the story of a Sightings crew sent to investigate a poltergeist haunting, eventually becoming victimized by the ghost themselves.

In 2003, a program called Unexplained Mysteries debuted in syndication. Although it did not have the same hosted news format like Sightings, it was produced by many of the same individuals involved with Sightings, and sometimes reused footage and graphics from the earlier series.

 

Sources:

http://www.sightings.com/1pages/history.html
http://en.wikipedia.org/wiki/Sightings_%28TV_series%29