According to a number of sources read including this very informative article (https://www.flapperpress.com/post/half-of-a-sixth-the-sixth-sense-the-night-gallery-syndication-package), The Sixth Sense originally aired as a 60-minute show, but was significantly altered for syndication. Episodes were edited down to a half-hour and recut with Rod Serling Night Gallery intros as both shows were part of the Night Gallery syndication package.