History SanitySlippage / FIlm

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* Francesco Dellamorte-Dellamore in ''Film/CemeteryMan'' - this is, in fact, the whole plot of the film.
* Zac Hobson in ''Film/TheQuietEarth'' begins suffering this when he realises that he may very well be the last human being alive. After the GoodTimesMontage, he begins dressing in women's clothes; he fills his garden with cardboard cutouts of celebrities; he fires his shotgun wildly at televisions; he declares himself President of the World and gives his [[NewEraSpeech inaugural address]] to the cutouts. [[FromBadToWorse And then the power goes out]], leaving Zac standing on his balcony, in total darkness and utterly insane. He gets [[BoredWithInsanity better]].
* Eric in ''Film/KillingZoe'' wasn't exactly the sanest person to begin with, but doing copious amounts of heroin, murdering several people, and setting off some explosives cause him to become batshit insane. As further proof, one of his favorite threats towards the end are "I'll fuck your bitch up the ass and give her AIDS!"
* Stéphane in ''Film/TheScienceOfSleep'' always had rather odd and confusing dreams and {{Imagine Spot}}s to help his cope with reality... by the end of the film he's unable to tell the difference between the two. While it doesn't go all the way to the end he holds shades of this.
* Happens to Komodo in ''Film/WarriorsOfVirtue'' after he [[spoiler:kills Master Chun]]. Although he was pretty zany from the start, he seemed to drop a few notches after the event.
* It is a thing to behold when this happens to [[Creator/DenzelWashington Alonzo Harris]] towards the end of ''Film/TrainingDay'', when he finally realizes that his corrupt methods held no power over anyone any longer, and he was truly going to die.
* Although Trevor Reznik from ''Film/TheMachinist'' had been acting odd ever since [[spoiler:he kills the boy]], when he starts harassing and assaulting everyone around him in a paranoid conviction that they are all out to get him you can tell he has finally completely cracked.
* Mike in ''Film/DeepEnd'' suffers this, mostly courtesy of Susan. The entire plot of the movie is Mike becoming her StalkerWithACrush -- except it's rather ''hard'' to [[WhatDoesHeSeeInHer understand why]], considering [[TheVamp her personality]] -- and in the end [[spoiler:his sanity finally snaps completely and he kills her.]] Given how she treated him throughout the entire movie, it's hard to sympathize with her.
* [[spoiler:Gordon]] in ''Film/{{Session 9}}'', although whether it's insanity or some sort of supernatural possession is left deliberately ambiguous.
* The main character in ''Film/IAmLegend'' suffers the beginnings of sanity slippage, asking a mannequin to talk to him because he promised his dog he'd ask, then breaking down in tears because the mannequin does not answer. It's even worse in the deleted scenes/uncut version. When he drives past the mannequin [[spoiler:trap]] the head of the mannequin actually ''moves'', and when he wakes up [[spoiler:after being saved from his suicidal assault]], he first sees the people in his house as his own wife and daughter [[spoiler:who had died years earlier.]]
* This trope is the whole point of ''Film/BlackNarcissus.'' All of the nuns find their flaws and emotional weaknesses slowly becoming more and more exaggerated. Things are worst with Sister Ruth, none too well to begin with, who turns into a StalkerWithACrush, and winds up [[spoiler: dying a DisneyVillainDeath when she attempts to murder her superior, Sister Clodagh.]]
* In the classic ''Film/TheTreasureOfTheSierraMadre'', Dobbs becomes increasingly unhinged as greed and paranoia brought on by GoldFever sets in, eventually leading him to try to murder everyone in his group.
* Ursula of ''Disney/TheLittleMermaid''. While not a good character, she was sane and composed during most of the film. However, when she transforms into Vanessa, its implied that she lost quite a bit of sanity (to the point of becoming a borderline AxCrazy) when turning into her, as she talks to her mirror in a manner similar to a schizophrenic, emits a psychotic grin when throwing a pin at a mirror's head with enough velocity to knock the mirror back, and most certainly kill a person had that been a human being, not to mention her cackling.
* ''Film/TheDarkKnight'': Harvey Dent screaming in silent agony in the hospital after realizing that [[spoiler: Rachel died]]. From there his Sanity Slippage following ComicBook/TheJoker's disturbing BreakingSpeech.
* [[{{Yandere}} Alex Forrest]] in ''Film/FatalAttraction'' grows increasingly unhinged the more Dan Gallagher tries to distance himself from her, until she reaches the point where she's willing to boil his daughter's bunny in the pressure cooker, kidnap her, and then try to knife his wife to death.
%%* Jafar in ''Disney/{{Aladdin}}''.
* In ''Film/TheAssassinationOfRichardNixon'' Samuel Byck (who was a real person) experiences this. Initially he just seems like a slightly delusional loser, but eventually he [[spoiler:plans to hijack a plane and fly it into the white house. Not to mention his intentions of killing his boss before that.]]
* In ''Cross of Iron'' Steiner goes through this as he's recovering in hospital. Even more so [[spoiler:in the ending when he goes into a laughing fit in the middle of battle after Captain Stransky asks him how to reload his firearm.]]
* The documentary ''Touching The Void'' is about the two climbers Joe Simpson and Simon Yates in their attempt to climb the Siula Grande mountain. After Joe Simpson has had his rope cut, and has been days without food or water, he eventually becomes delirious; as he presumes himself to be close to death, the song 'Brown Girl in the Ring' by Boney M gets stuck in his head, which is a song that he hates.
* In Creator/WernerHerzog's ''Film/HeartOfGlass'', the death of a foreman glassmaker has deprived a 18th century glass factory of the secret recipe for red glass. The movie is driven by the factory owner, threatened by bankruptcy, progressively losing his already weak grasp of sanity.
* In ''Film/MulhollandDrive'' all it took to send the mentally unstable protagonist over the edge was some knocking on the door.
* ''{{Film/Repulsion}}'' is about a troubled young woman stumbling deeper and deeper into madness.
* In ''{{Film/Shine}}'', David starts off reasonably normal but as time goes on becomes increasingly manic and starts being less intelligible, peaking when he plays Rachmaninoff's Third Piano Concerto and in the aftermath.
* In ''Film/{{Thor}}'', Loki's sanity starts to slip after he discovers [[spoiler: his true Frost Giant heritage]]. By the time he is fighting Thor at the end of the film, he is on the verge of LaughingMad and has clearly taken a [[JumpingOffTheSlipperySlope dive off of the slippery slope]]. The slippage continues into ''Film/{{The Avengers|2012}}'', where it's clear that his [[spoiler: fall through the Bifrost]] has left him AxeCrazy and more than a little unhinged.
* In ''Film/TheGamersHandsOfFate'', Gary continuously hallucinates horrible things about Chibichan, a Pokemon-esque creature, because its creation brought about the cancellation of one of Gary's favorite shows ever, Ninja-Dragon Riders.
* ''Film/{{Elysium}}'': Not that he was entirely sane to begin with, but Kruger becomes noticeably more unhinged following [[spoiler:his facial reconstruction.]]
* In ''Film/XMenTheLastStand'', this is why Xavier had neutered Jean Grey's mental powers to keep the Phoenix hidden. And once she's unleashed...
* Mac in ''Film/{{Predator}}'', after [[spoiler: Blaine's]] death.
* ''Film/MyLifeAsADog'': No this movie has nothing to do with turning into a dog. This movie is about the sanity slippage of Ingemar as he starts acting more like a dog and less like a boy. He's losing everything and compares himself to Laika, the first dog sent into space and left to die. Uncle Gunner is challenged with trying to reach this boy before he's lost forever.
* ''Film/VampiresKiss'' is the story of Nicolas Cage's character, the businessman Peter Loew, slowly becoming crazy, firmly convinced he's turning into a vampire.
* ''Film/StonehearstAsylum'': Lamb. While he his methods towards mental health are humane in and of themselves, he keeps the real staff locked up, puts a homicidal killer like Finn in charge of security and shows no remorse when Finn kills two escaped staff members and later one of the patients, electroshocks Salt into amnesia and tortures Newgate.
* In ''Film/{{Fury 1936}}'', the hero undergoes a sanity slippage in the third act, caused by the guilt that is weighing heavily upon him. He starts [[HearingVoices hearing Katherine's voice]] when watching the shop window, he sees the number 22 on the calendar at the bar and can't help but think of the 22 accused. After he leaves the bar and walks along the street, he sees some of the faces of the mob in a store window. Frightened, he begins running down the empty road as if he's being chased, the camera follows him, only showing the audience what seems to be following Joe - nothing, only his conscience.
* In ''WesternAnimation/TheSpongeBobMovieSpongeOutOfWater'', ''everyone'' in Bikini Bottom loses it after the formula is stolen, becoming savage and selfish. Sandy is a more noticeable example, as her treedome is converted into a RoomFullOfCrazy, and she keeps prophesying about [[TheEndOfTheWorldAsWeKnowIt "The End"]].
* Dr. Scott feels that's what is happening to him in "Don't Dream It, Be It" from ''Film/TheRockyHorrorPictureShow'':
-->Ach![[note]][[AudienceParticipation CHOO!]][[/note]] We've got to get out of this trap
-->Before this decadence saps our wills.
-->I've got to be strong, and try to hang on
-->Or else my mind may well snap[[note]][[AudienceParticipation CRACKLE POP!]][[/note]]
-->And my life will be lived[[note]][[AudienceParticipation IN A BOWL OF RICE KRISPIES]][[/note]] for the thrills.
* ''Film/MadMaxFuryRoad'':
** Max certainly lives up to his name by this point. He's haunted by voices and hallucinations of the people he's watched die and failed to save over the years, [[Film/MadMax1 most of all his wife and son]], he twitches and mutters to himself often, and he shows signs that he's spent so long on his own that he's [[NoSocialSkills forgotten how to interact with people normally]]. These all point to signs of PTSD and schizophrenia.
** On the villainous side, the Bullet Farmer starts out relatively understated and sedate, snarking about how they're committing dozens of cars to a "family squabble". After he's blinded, however, he begins ranting about he's the conductor of the Choir of Death, firing machine guns at nothing just because he enjoys shooting, and referring to his guns as "Brother Heckler" and "Brother Koch".
* ''Film/{{Reality}}'', is the story of the protagonist's descent into insanity. [[spoiler: Although it is hinted that he wasn't particularly stable to begin with.]]
* The central plot of ''Film/AWomanUnderTheInfluence''. Mabel, a psychologically fragile housewife, has a full-on breakdown brought on by the pressures of motherhood and the stress of being married to a mean, aggressive husband. Early in the film she is doing odd things like addressing people who aren't there or calling people by the wrong name. Eventually she's committed to an asylum.
* In ''Film/TheDisappointmentsRoom'', Dana suffers this once the room is unlocked, thanks to the ghost of the judge.
* ''Film/AssassinsCreed2016'': Callum, due to having to be dragged into the Animus the first two times, starts hallucinating his ancestor severely enough to ''spar with him'', as well as going LaughingMad for a while. There's also the other Assassins who are left catatonic due to being forced into the Animus against their will.
* In Assamese anthology horror film ''Kothanodi'' (''The River of Fables''), the character Dhoneshwari descends rapidly into a delusional half-dream state where she imagines the python she married her daughter to is adorning her with jewellery on her wedding night, when it reality the python is [[spoiler:eating her.]]
* In the documentary ''Film/HeartsOfDarknessAFilmmakersApocalypse'', which chronicles the TroubledProduction of ''Film/ApocalypseNow'', director Creator/FrancisFordCoppola summarizes: "There were too many of us, we had access to too much money, too much equipment, and little by little we went insane."
* ''Film/TheManWhoKilledDonQuixote'': Javier started losing his sanity when Toby was filming ''The Man who killed Don Quixote''. And it progressively happens to Toby as well ten years later.
* ''Film/{{Accident}}'': Following Fatty's death (which he is convinced was aimed at him), the Brain begins a rapid descent into paranoia: seeing conspiracy at every turn.
* ''Film/Ms45'': At first, Thana only kills men who attempt to take advantage of her. Later, as she loses more of her sanity, she kills any man unlucky enough to be near her.
* General Jack D. Ripper goes through this as ''Film/DrStrangelove'' unravels. He sends his base's squadron of B-52s to attack Russia, telling his attache Group Capt. Lionel Mandrake that it's because Washington has been attacked. What Ripper eventually confesses is that he's impotent and that the Russians are responsible for it through fluoridation of the water. Everyone in the Pentagon war room (except, maybe, for General Turgidson) that Ripper went off his nut for pre-empting the failsafe mechanisms the attack plan called for.
* In ''Film/TheHandsOfOrlac'', Orlac's sanity starts to slip from the time he wakes up in the hospital with his new hands. He becomes possessed of the desire to kill and believes that along with the hands he has acquired the murderer's predisposition to violence. He decides he can no longer touch anyone with his hands lest he be overwhelmed by the compulsion to kill them. Things get worse as the movie goes on.
* ''Film/{{Jungle}}'': Yossi's mental states is slowly degrading almost from the start of the trek into the jungle. However, once he is stranded by himself in the HungryJungle, he goes downhill rapidly. At his lowest point, he creates an ImaginaryFriend to accompany him.
* ''Film/TheDescent'' is a British horror film about a traumatised woman named Sarah who goes spelunking with some friends in the Appalachians, but then they get trapped in a cave-in. When things go FromBadToWorse and the party discovers that the cave is home to [[TheMorlocks cannibalistic degenerates]], the women [[DoubleMeaningTitle descend]] into savagery to survive and Sarah completely loses it.
* ''Film/Joker2019'': The Joker undergoes considerable sanity slippage throughout the film, [[DoomedByCanon unsurprisingly.]] At the beginning of the movie, he is an already mentally unstable, struggling man who then deteriorates even more after experiencing multiple stressors around the same time as he loses access to both antipsychotic medication and therapy. By the end of the movie, [[UnreliableNarrator his point of view becomes so skewed]] that it is [[ThroughTheEyesOfMadness unclear whether some events really happened or only happened in the Joker's mind. There are also whole scenes that definitely only happened in the Joker's mind, but some are left ambiguous.]]
* ''Film/HorseGirl'': Sarah starts off as a fairly normal if slightly eccentric woman, but over the course of the movie she becomes more and more out of touch with reality. Her missing memories and strange dreams intensify, she becomes more and more insistent on the reality of her theories about alien abduction and being a clone, and she becomes increasingly obsessed with bizarre, craft-supply based defenses against the aliens. She becomes more emotionally unstable as well, shedding her meek and understated demeanor from earlier on and becoming prone to anxiety and fits of hysterics.
* ''Film/AViewToAKill'': While he was already mentally unstable, Max Zorin loses whatever sanity he had as the film progresses. After Bond foils his scheme to trigger an earthquake in the San Francisco Bay Area to corner the microchip market, Zorin goes nuts to the point of ''[[BadBoss gunning down his minions]] [[ForTheEvulz out of pure sadism]]'' and wildly swinging [[AxCrazy a literal axe]] against 007 during their showdown. A justified trope, as Zorin is the [[FreudianExcuse end result]] of a SuperBreedingProgram to create the ideal SuperSoldier for the Nazis GoneHorriblyRight — while most of the pregnancies failed, the few babies that survived became gifted later in life — but also totally psychopathic.
* In ''Film/{{Killdozer}}'', Dutch starts losing it after Mac dies: first becoming paranoid and then telling long, pointless stories. By the end, he decides that he wants to go for a swim while the killer bulldozer is still on the loose.
* ''Film/TheManFromColorado'': Four years of constant fighting and bloodshed have turned Owen into a BloodKnight. After the war ends, his sanity continues to erode and he becomes a HangingJudge, finding an excuse to execute anyone brought before him, and he slides deeper and deeper into paranoia: eventually blockading the town to prevent anyone leaving and setting fire to part of it to flush out his imagined enemies.
* ''[[Film/AMIArticifialMachineIntelligence A.M.I.: Artificial Machine Intelligence]]'': Cassie's sanity starts going downhill after [[AIIsACrapshoot A.M.I.]] starts hypnotizing her into killing people. [[spoiler:By the end of the movie, she's surrounded herself with phones programmed to sound like her parents, her boyfriend, and a baby, and treats them all like they're real people. So, yeah, safe to say she's completely lost it at that point.]]
* In ''Film/TheDeadCenter'', Dr. Forrester's sanity clearly took a hit when [[spoiler: the demon briefly attacks him for the first time.]] He's left with flashing hallucinations of previous victims and is basically a nervous wreck. He's still well enough to function and [[spoiler: beat Michael Clark to death]], but [[DrivenToMadness how much sanity he has left by the end of the movie is debatable.]]
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* ''Film/{{Accident}}'': Following Fatty's death (which is convinced was aimed at him), the Brain begins a rapid descent into paranoia: seeing conspiracy at every turn.

* ''Film/MadMaxFuryRoad'': Max certainly lives up to his name by this point. He's haunted by voices and hallucinations of the people he's watched die and failed to save over the years, [[Film/MadMax1 most of all his wife and son]], he twitches and mutters to himself often, and he shows signs that he's spent so long on his own that he's [[NoSocialSkills forgotten how to interact with people normally]]. These all point to signs of PTSD and schizophrenia.

* In the documentary ''Film/HeartsOfDarknessAFilmmakersApocalypse'', which chronicles the TroubledProduction of ''Film/ApocalypseNow'', director Creator/FrancisFordCoppola summarizes:
-->"There were too many of us, we had access to too much money, too much equipment, and little by little we went insane."

* ''Film/MadMaxFuryRoad'': Max certainly lives up to his name by this point. He's haunted by voices and hallucinations of the people he's watched die and failed to save over the years, [[Film/MadMax1 most of all his wife and daughter]], he twitches and mutters to himself often, and he shows signs that he's spent so long on his own that he's [[NoSocialSkills forgotten how to interact with people normally]]. These all point to signs of PTSD and schizophrenia.

* ''Film/MadMaxFuryRoad'': Max certainly lives up to his name by this point. He's haunted by voices and hallucinations of the people he's watched die and failed to save over the years, [[Film/MadMax most of all his wife and daughter]], he twitches and mutters to himself often, and he shows signs that he's spent so long on his own that he's [[NoSocialSkills forgotten how to interact with people normally]]. These all point to signs of PTSD and schizophrenia.

* Mike in ''Film/DeepEnd'' suffers this, mostly courtesy of Susan. The entire plot of the movie is Mike becoming her StalkerWithACrush -- except it's rather ''hard'' to [[WhatDoesHeSeeInHer understand why, considering]] [[TheVamp her personality]] -- and in the end [[spoiler:his sanity finally snaps completely and he kills her.]] Given how she treated him throughout the entire movie, it's hard to sympathize with her.

* In Assamese anthology horror film ''Kothanodi (''The River of Fables''), the character Dhoneshwari descends rapidly into a delusional half-dream state as she imagines the python she married her daughter to is adorning her with jewellery on her wedding night, when it reality the python is [[spoiler:eating her.]]

* It is a thing to behold when this happens to [[DenzelWashington Alonzo Harris]] towards the end of ''Film/TrainingDay'', when he finally realizes that his corrupt methods held no power over anyone any longer, and he was truly going to die.

* ''Film/TheDarkKnight'': Harvey Dent screaming in silent agony in the hospital after realizing that [[spoiler: Rachel died]]. From there his Sanity Slippage following SelfDemonstrating/TheJoker's disturbing BreakingSpeech.

* ''/Film/AssassinsCreed2016'': Callum, due to having to be dragged into the Animus the first two times, starts hallucinating his ancestor severely enough to ''spar with him'', as well as going LaughingMad for a while. There's also the other Assassins who are left catatonic due to being forced into the Animus against their will.

* Jafar in ''Disney/{{Aladdin}}''.

* In ''Film/TheDisappointmentsRoom'', Dana suffers this once the room is unlocked, thanks to the ghost of the judge.