The film stars Teresa Palmer, Gabriel Bateman, Alexander DiPersia, Billy Burke, and Maria Bello.

[4] Produced by Heisserer, Lawrence Grey, and James Wan, the film was shot in Los Angeles from June to August 2015.

It had its world premiere at the Los Angeles Film Festival on June 8, 2016, and was released in the United States and Canada by Warner Bros. on July 22, 2016.

Rebecca finds a box of medical records and research in Paul's office, which reveal that Sophie was admitted to a mental hospital as a child.

While there, she befriended a young patient named Diana, who suffered from a severe skin condition that meant she could not go out in sunlight.

In the end, Diana was accidentally reduced to ashes by the hospital staff when they tried to perform an experimental treatment on her under intense light.

As she climbs the stairs, Diana reveals that she killed Rebecca's father years ago because, like Paul, he tried to help Sophie recover from her trauma.

Although the film did not win the competition, the short soon went viral, leading to Sandberg being contacted by several agents, to the point where he had to develop a spreadsheet to keep track of them all.

[5] One of the contacts was Lawrence Grey who wanted to collaborate with James Wan in order to produce a feature-length version.

Although Wan enjoyed the short, he was hesitant that it could be turned into a feature until Sandberg produced a treatment for the feature-length version.

Once in Hollywood the two were unable to get an apartment due to not having a US credit score, forcing them to rent Airbnb on a monthly basis.

[5] Sandberg originally based the character of Rebecca on a real girl that he knew who was suffering from depression, and who was engaging in self-harm, which is why Rebecca has scars on her arms, but the development of the film made it less about depression and more of a ghost story in which Diana would have been the real person who died and became a ghost.

[17] The film exceeded expectations and earned $21.7 million in its opening weekend, finishing at third place behind fellow newcomer Star Trek Beyond and holdover The Secret Life of Pets.

The site's critical consensus reads, "Lights Out makes skillful use of sturdy genre tropes—and some terrific performances—for an unsettling, fright-filled experience that delivers superior chills without skimping on story.

[26] Lucy O'Brien of IGN gave the film 7/10, saying: "[w]ith an unnerving monster at its core, great cast and relentless final sequence, Light's [sic] Out is a debut director Sandberg should be proud of.

A clunky script occasionally loosens its grip on the nerves, but chances are Diana will still have you sleeping with the lights on for a good while after leaving the theatre.

"[28] Justin Lowe of The Hollywood Reporter wrote, "[a] surprisingly maternal horror movie that relies as much on fraying emotional bonds as supernatural suspense to create tension, Lights Out deals with an array of primal fears that threaten to unravel a family's fundamental relationships, along with their sanity.

"[29] Jeannette Catsoulis of The New York Times wrote, "[s]packling over any copycat cracks with strong acting and fleet editing, Lights Out delivers minimalist frights in old-school ways.

James Berardinelli of Reelviews gave 2 stars out of 4, saying: "[u]nfortunately, the film stumbles, offering too few legitimate scares and displaying an overreliance on traditional horror movie clichés."

Berardinelli detested the film's camerawork, described characters as being "thinly drawn", and the screenplay as "spending inordinate amount of time providing a backstory..."[31] Rex Reed of Observer gave 1 star out of 4, saying: "the film's screenplay focuses almost entirely on the number of resourceful and ingenious ways the characters dream up to keep the lights on, stave off the next attack and stay alive—lights from candles, flashlights, cellphones, the car in the driveway—before the batteries die; The fun wears out fast and so does the "gotcha" factor.

"[32] In July 2016, a week after the film's release, it was announced that New Line Cinema and Warner Bros. Pictures had greenlit a sequel.