The Ending was an important event in the Glade. It began when Teresa entered the Glade, and included the removal of the Glade's sun, and caused the doors of the Maze to remain open at night. This was also the point at which the Creators stopped giving weekly supplies to the subjects, thereby forcing them to venture outside the protection of the Glade.
Teresa's arrival in the Glade marked the beginning of the Ending. When she woke up after several days in coma, the artificial sun disappeared and left blank grey sky that, according to Chuck, resembled a ceiling. In consequence after a few days, the plants began to wilt. The weekly supplies were cut, thus limiting the available food. Also the doors stayed open all night, so the Grievers could come and strike the Gladers – in the book, they came several nights, each time taking one Glader; in the film, they raided the Glade only once, but killed almost half of the Gladers.