History SanitySlippage / WesternAnimation

** After the TimeSkip between episode 3 and 4, [[spoiler: Jinx - formerly Powder - has experienced this ''severely'', hallucinating Mylo and Claggor talking to her as a means of coping with having [[MyGreatestFailure caused their deaths]].]]

* ''WesternAnimation/{{Arcane}}'': As Viktor is being wracked by illness and Jayce is led astray by the council's politics, he becomes worryingly obsessed with his work, [[spoiler:and after learning he will die of his illness soon, implicitly over how Hextech could prolong life]]. After becoming disillusioned enough with Heimerdinger's resistance to progress that could [[spoiler:save his and others' lives, he goes off to find Singed again and acknowledges that his extreme means to sustain life are ultimately right. He willingly takes [[PsychoSerum Shimmer]] and essentially performs BloodMagic all in an attempt to survive.]]

* Rabbit has experienced this at various times in the Disney ''Franchise/WinnieThePooh'' franchise, often having to do with Tigger. His thinking he has seven years bad luck because of a broken mirror in "Luck Amuck" from ''WesternAnimation/TheNewAdventuresOfWinnieThePooh'' is just one of many, many examples.

** Princess Luna experiences this a thousand years before the time of the series. Literally consumed with [[GreenEyedMonster jealousy and anger]] towards the ponies rejecting [[TheSacredDarkness her beautiful night]] in favour of Celestia's day, she [[FaceHeelTurn transforms into]] [[SuperpoweredEvilSide Nightmare Moon]] and tries to enact [[TheNightThatNeverEnds eternal night]] in a stubborn attempt to ''force'' the ponies to love her, showing that even a [[PhysicalGod Physical Goddess]] isn't immune to CMFIS. In [[Recap/MyLittlePonyFriendshipIsMagicS2E4LunaEclipsed "Luna Eclipsed"]] she runs the risk of having to bear these insecurities all over again when the ponies begin to reject her once more, but fortunately Twilight is there to help.

** In ''[[Recap/MyLittlePonyFriendshipIsMagicS4E23InspirationManifestation Inspiration Manifestation]]'', the more Rarity uses [[TomeOfEldritchLore the eponymous book]]'s power, [[WithGreatPowerComesGreatInsanity the more deranged she becomes.]]
** Rainbow Dash's turn comes in ''[[Recap/MyLittlePonyFriendshipIsMagicS5E5TanksForTheMemories Tanks For The Memories]]'', where her anxiety at having her beloved tortoise hibernate for the winter drives her to try and ''stop winter from happening''.
** The episode ''[[Recap/MyLittlePonyFriendshipIsMagicS7E10ARoyalProblem A Royal Problem]]'' shows us that not even ''Celestia herself'' is immune to this. After Starlight switches her magic with Luna's Celestia takes over her sister's nightly duty and expected them to be easier, only to quickly find out that because it's nighttime all the ponies in Equestria are asleep, which leaves her without company. She quickly start talking to herself. A lot. Luna admits to talking to herself as well.
** Queen Chrysalis goes through this in ''[[Recap/MyLittlePonyFriendshipIsMagicS8E13TheMean6 The Mean 6]]'' after being dethroned as Queen of the Changelings for many months and having to live in the Everfree Forest. When she tries to make evil doubles of the Mane 6 through some trees, she speaks to them as if they were alive.

** Then, in "[[Recap/StevenUniverseFutureS1E18EverythingsFine Everything's Fine]]", [[spoiler:Steven goes completely off the rails. He returns after visiting the Diamonds, now stuck as the large, muscular man he became in "Fragments". He tries to head into Little Homeworld to help out and generally have a normal day, but his emotional state [[PowerIncontinence causes his powers to go completely haywire]], up until the point where an excited shout over a baseball he caught produces a shockwave that levels several buildings. Steven then heads back to the house, where Greg, Connie and the Gems are gathered for an intervention, which Steven... does not take well, his body starting to violently contort while he cries out in pain. When Connie proposes taking Steven back to the hospital, the Gems react in shock, because he never told them he went]]. Steven responds by playing down his issues all throughout ''Future'', likening his crashing the van to "a little disagreement" and a "rite of passage". In the same breath, he mentions that he almost murdered White Diamond and "only" shattered Jasper but thanks to his powers, he can fix everything with no one being the wiser. At this point, Steven collapses to the floor and proclaims himself a fraud, quietly sobbing to himself. Then he screams that he's a monster and the episode ends with [[JumpScare a mass of pink spikes bursting out of his back]].

** Candie the Chipmunk gets one in "I Got Yer Can" after Slappy takes revenge at her.

** It eventually hits a point where he begins to put others in danger starting with "[[Recap/StevenUniverseFutureS1E15MrUniverse Mr. Universe"]], crashing Greg's van after giving him a TheReasonYouSuckSpeech for never giving him a proper childhood.

** Fry suffers this in "Insane in the Mainframe" as a result of being a human confined to a robot asylum.
** In "Mobius Dick", Leela goes insane when she becomes obsessed with trying to kill a space whale in revenge.

* If you look closely at some of the text in Journal 3 on ''WesternAnimation/GravityFalls'', it seems like the Author underwent something like this. [[spoiler: He did indeed, as a result of being manipulated by Bill Cipher into building a device that would destroy the world. However, his case was relatively mild and he managed to pull himself back together - probably a result of his trip to another dimension.]]
** Mabel slowly starts losing it in the season 1 episode "The Time Traveler's Pig" [[spoiler: after Dipper's time travel antics cause her to lose her pet pig]]. After handing out calculators to people across eight centuries, she eventually breaks completely and starts banging her head against a post and doesn't stop for a month, during which time she grows vines and gets a shoulder snail. [[spoiler: Fortunately, it's temporary, and getting her pig back seems to resolve all the problems, but this example is played more for drama than laughs, despite its absurdity]].
** Old Man [=McGucket=] [[spoiler: helped build the machine in Stan's basement thirty years ago, but an accident with the device heavily traumatized him. He then built a gun that would erase the memory from his mind, creating the Society of the Blind Eye so that others wouldn't be freaked out or traumatized by the weirdness of Gravity Falls. However, repeated use of the memory wipe took a toll on [=McGucket's=] sanity, until he was reduced to the junkyard dwelling town kook he is today. It's also implied that he never totally forgot the event that he originally tried to forget in the first place, as evidenced by him making a symbol representing [[BigBad Bill Cipher]], which aided in his fall.]]

* Candace from ''WesternAnimation/PhineasAndFerb''. It's not gradual and it's not regular like most examples, but it's definitely there. Seriously, this girl needs help. She has a psychological need to bust, it's shown at least twice that she can't go without it. That doesn't smack of good mental health...
** If it wasn't clear before, the episode "Monster From ID", which takes place largely in Candace's subconsciousness, seals it. Candace's head is one messed up place.

* ''WesternAnimation/ThePowerpuffGirls'':

** Stu also loses it in "Angelica Breaks a Leg", when he's forced to take care of Angelica after she pretends to have broken her leg.

'''Stu:''' (''wearily resigned'') Because I've lost control of my life.

** In season 3, Catra experiences this after her jealousy toward Adora pushes her to the breaking point. She activates the interdimensional portal, fully aware that it will destroy Etheria and herself, because she wants to deny Adora another victory. In season 4, multiple stressors (including guilt over exiling Entrapta, Scorpia's defection, and the emptiness she feels despite all the Horde's military victories) undermine her sanity. Double Trouble's BreakingSpeech in "Destiny, Part 2" leaves her broken and despondent.
** In "Coronation", Catra's lie about Entrapta's supposed "betrayal" triggers Hordak's nervous breakdown. He broods in the wreckage of the portal machine, demonstrates unsound judgment, and reacts violently to the mere mention of Entrapta. He regains his sanity for most of season 4, but when Double Trouble reveals to him that Catra exiled Entrapta, he attacks Catra in a [[RoaringRampageOfRevenge berserk rampage]].

** The episode "Springfield Up" contains a very swift summary of how doctor/lawyer Eleanor Abernathy went off her rocker and became the town's yowling cat lady.
** Frank Grimes learns the hard way in "[[Recap/TheSimpsonsS8E23HomersEnemy Homer's Enemy]]" that being the OnlySaneMan in a CrapsackWorld is not conducive to one's long term mental health.
** Homer himself does so in ''The Shinning'' segment of "[[Recap/TheSimpsonsS6E6TreehouseOfHorrorV Treehouse of Horror V]]" when the cable stops working and they run out of beer, all thanks to Mr. Burns.
--->'''Homer''': So what do you think, Marge? All I need is a title. I was thinking along the lines of "No TV and no beer make Homer something something"...\\
'''Marge''': "Go crazy?"\\
'''Homer''': '''''Don't mind if I do!!''''' (''proceeds to go crazy'')

** In "[[Recap/TheSimpsonsS6E1BartOfDarkness Bart of Darkness]]" Bart breaks his leg at the start of summer and begins to GoMadFromTheIsolation.

--> '''Marge:''' Homer, your growing insanity is starting to worry me.
* In the ''WesternAnimation/TheSmurfs2021'' episode "Leaf It Alone", the Smurfs slowly go crazy from losing the Sarsaparilla. Some try to sacrifice Dimwitty to get it back.

** "1%" ends with the implication that Cartman's sociopathic tendencies are growing into a full blown psychosis. Even without any greater implications, you can see his sanity suffer with each stuffed animal destroyed.
** Randy in "A Nightmare on Face Time". Complete with a shot-for-shot, line-for-line {{homage}} to Creator/JackNicholson and ''Film/TheShining''.
** Randy’s SanitySlippage is a recurring arc throughout the series, with him going from a BumblingDad to a selfish ManChild, and finally the deranged, murderous [[CorruptCorporateExecutive head of a weed farm.]]
** Stan also underwent this to a lesser extent in later seasons, becoming far more cynical and apathetic to the world around him after Wendy breaks up with him and the events of "You’re Getting Old." The ending of "Ass Burgers" shows he’s resorted to using alcohol to get through the day.
* ''WesternAnimation/SpongeBobSquarePants'' and Mr. Krabs try to keep their sanity when they believed they killed the health inspector. [[spoiler:Turns out that the inspector is still alive, and the Krusty Krab passes inspection.]]
** In "Pickles", [=SpongeBob=]'s life takes a turn for the chaotic after a JerkAss customer claims that he forgot the titular condiment. By which we mean he tries to cook his bicycle and hangs the toaster on his front door.
** Poor Squidward. In between being the entire ocean's ButtMonkey and victim to the constant shenanigans of his next door neighbors, [=SpongeBob=] and Patrick, it's no wonder he's been shown to break down into a sobbing wreck or fits of maniacal laughter when the AmusingInjuries and ever-present failures prove too much to handle. In "Squid's Day Off" Squidward tricks [=SpongeBob=] into running the Krusty Krab all by himself while he takes a day off, but he keeps imagining [=SpongeBob=] destroying the Krusty Krab and repeatedly goes back and forth to and from his house. While taking a bath he hallucinates [=SpongeBob=] is watching him and runs off to the Krusty Krab wearing only bubbles.

--->''(from "Stuck in the Wringer")''\\

'''[=SpongeBob=]:''' ''(watching static on TV)'' My favorite show. ''(the TV dies)'' Ha, ha, I love that part!
** Mr. Krabs goes crazy when the squeaky noise of the rubber boots he gave Spongebob becomes too much to bear.
** In "Clams" after Mr. Krabs loses his millionth dollar we see him slowly go completely insane. The cut back to Mr. Krabs, who begins giggling maniacally [[EyeScream and tears his two eyes out, using them as a jumprope]] is genuinely disturbing.
** When Spongebob decides to live with the jellyfish in "Nature Pants," Patrick, [[CloudCuckooLander who wasn't all there]] [[TheDitz in the first place]], goes ballistic, planning on catching Spongebob and keeping him in a jar.

** In the non-canon ''WesternAnimation/UncleGrandpa'' crossover episode, Pearl, who is the logical (most of the time), brainy perfectionist of the team, becomes increasingly unhinged and suffers at least three mental breakdowns from dealing with Uncle Grandpa's weirdness. This is even emphasized by a significant downgrade in her appearance and animation and major [[ChewingTheScenery scenery chewing]] by her voice actress. It overlaps with temporary Flanderization because while Pearl is susceptible to bouts of hysterics and irrational behavior, she's never lost it to this degree before or since.
** In "Chille Tid", it is implied to have happened to Jasper after [[spoiler: she is trapped in Malachite by Lapis, when she sees Steven again, crawling towards Steven with an insane look on her face and a tone in which she sounds like she plans on eating him alive.]]
** Peridot's stay on Earth has...not been good for her personal stability. Oddly enough, while in most cases of this trope there's a direct correlation between how conclusively one has cracked up and how much of a {{Jerkass}} one is, in the later stages of her SAN meter's decline, Peridot actually gets ''nicer'', to the point where she [[HeelFaceTurn defies Yellow Diamond and officially becomes a Crystal Gem]]; this realization led to her most impressive freakout to date.
--->'''Peridot''': (into her tape recorder) I'm a traitorous clod! They'll never want to think about what I've done again!\\
(sighs, rewinds recording)\\
'''Peridot (recording)''': I'm a traitorous clod! I never want to think about what I've done again!\\
'''Peridot''': (grins widely) YEAHAHAHAHA!\\
[...]\\
'''Steven''': Peridot, are you gonna be okay?\\
'''Peridot (recording)''': I'm a traitorous clod! (rewind) -traitorous clod!\\
'''Peridot''': (''turns around with a maniacally-cheerful grin'') [[BluntYes NO!]]
* ''WesternAnimation/StevenUniverseFuture'' is having a field day with this trope, enough to be mentioned separately from the original series.
** Beginning with "Little Homeschool", we are shown that Steven has an unhealthy amount of repressed anger, resulting in him [[spoiler:getting a new power where he turns pink and gains violent tendencies whenever he's angry]]. This trend continues throughout the series. Steven also seems to have an unhealthy obsession with helping people, which comes back to bite him later.
** In "Rose Buds" and "Volleyball", Steven is shown to be experiencing repressed trauma related to [[spoiler:the whole Pink Diamond/Rose thing and all the horrible things she did]], which seems to be the other major trigger for [[spoiler:Pink Steven mode]]. As usual, Steven bottles up his feelings.
** In "A Very Special Episode", Steven runs himself ragged trying to help multiple people at the same time, eventually collapsing from exhaustion. Unlike the other examples on this page, it's PlayedForLaughs, and [[spoiler:it's ambiguous how much of this episode is even canon anyway]].
** In "Snow Day", it's revealed Steven has a constantly-busy schedule and refuses to ever take a day off.

** Steven's sanity takes a nosedive in [[WhamEpisode "Little Graduation"]]. He discovers that [[spoiler:Sadie has broken up with Lars and is now dating a person named Shep]], [[spoiler:the Suspects split up and Sadie is performing alongside Shep]], and that [[spoiler:Lars and the Off Colors are going into space after the graduation]]. Steven [[spoiler:has a mental breakdown]] over all of this, and accidentally [[spoiler:uses his powers to trap everyone in a dome]]. The cherry on the cake is that Steven [[spoiler:projects his issues onto Lars instead of admitting that he's the one who needs help]]. No wonder he [[spoiler:leaves Little Homeschool]], which makes it worse as he now feels that [[spoiler:he has no purpose anymore]].
** In the next episode, which is an even bigger WhamEpisode, Steven has taken up gardening, except [[spoiler:he named all his plants after people he knows and talks to them, even stating that the flower named Lars is stuck in the ground and can't run off into space]]. This is PlayedForLaughs, but the rest of the episode is '''not'''. Steven's pet cactus gets [[spoiler:used as an emotional punching bag for Steven to vent his bottled-up feelings on]]. This comes back to bite him when [[spoiler: the cactus learns to talk and starts repeating the things that Steven's said about the gems... right in front of them]]. This causes Steven to [[spoiler:get mad at and abuse]] the cactus, who does not take it well and attacks him, mutating into a botanical monstrosity. At the end of the episode, [[DramaticallyMissingThePoint Steven learns that]] [[spoiler:he shouldn't talk about his problems at all]]. The most heartbreaking part is that [[spoiler:the gems know something is wrong and keep reaching out to Steven, but he rejects their help because he feels like he can't talk to them.]]

** Steven gets to spend some quality time with Peridot when they watch the reboot of Camp Pining Hearts, and when they find it lacking, Peridot comes up with the idea for Steven to dream a new and better reboot. Steven goes along with the idea at first, but quickly gets tired out and stressed [[spoiler: when his own issues start twisting the dreams in weird ways. Fortunately, this one ends a little better when the last dream has Steven literally spelling out that he's uncomfortable with the situation and Peridot, recording his dreams, realises that she was pushing him too hard and he that he was willing to do anything just to have ''someone'' spend time with him so he didn't have to be alone.]]
** Later, after getting to spend some quality time with Connie and reaffirming that he can still be her friend even with her new friends around in "Bismuth Casual", Steven begins to worry that Connie moving away for college will leave him without her. Talking to both Ruby and Sapphire individually, [[spoiler: they convince him to propose which does not go well]]. This sets up for "Growing Pains" in which Connie's mother gives Steven a check-up when his [[PowerGlows gem powers]] start going mad and causing him to swell randomly. She eventually discovers [[spoiler: that Steven's skeleton is cracked, and that all the events of the last five seasons might not have healed mentally and left Steven's body reacting to all stresses as if he was in danger of dying]].
** In "Growing Pains", Priyanka makes a diagnoses that Steven has been through so many high stress situations (both physically and psychologically) at such a young age, that his body chemistry reacts in a manner disproportionate to the stimulant. Simply put, the relatively minor Era 3 problems that he has been facing (his friends leaving to bigger and better things, Connie turning down his proposal, etc.) feel like the life-or-death scenarios of Era 2 to him, giving him anxiety attacks that manifest as PowerIncontinence.
** It eventually hits a point where he begins to put others in danger starting with "Mr. Universe", crashing Greg's van after giving him a TheReasonYouSuckSpeech for never giving him a proper childhood.
** In "Fragments", Steven seeks out Jasper and trains with her to control his powers in order to prevent them from causing any harm, but Jasper proves to be a [[SocialDarwinist bad influence on him]], with him getting progressively more and more ruthless to the point where his AllLovingHero traits completely disappear. His rematch with Jasper then ends with him [[spoiler:shattering her, though he's able to revive her later on.]]
** In "Homeworld Bound", it only gets worse. After realizing that White Diamond was the source for all his problems and trauma, Steven attempts to [[spoiler:'''shatter''' her by using White's puppet powers to force her head against a pillar. Afterwards, he begins to go under a transfomation similar to the one he went through in "Fragments", but with his hair starting to resemble '''Pink's'''.]]
** Then, in "Everything's Fine", [[spoiler: Steven goes completely off the rails. He returns after visiting the Diamonds, now stuck as the large, muscular man he became in "Fragments". He tries to head into Little Homeworld to help out and generally have a normal day, but his emotional state [[PowerIncontinence causes his powers to go completely haywire]], up until the point where an excited shout over a baseball he caught produces a shockwave that levels several buildings. Steven then heads back to the house, where Greg, Connie and the Gems are gathered for an intervention, which Steven... does not take well, his body starting to violently contort while he cries out in pain. When Connie proposes taking Steven back to the hospital, the Gems react in shock, because he never told them he went.]] Steven responds by playing down his issues all throughout ''Future'', likening his crashing the van to “a little disagreement” and a “rite of passage”. In the same breath, he mentions that he almost murdered White Diamond and “only” shattered Jasper but thanks to his powers, he can fix everything with no one being the wiser. At this point, Steven collapses to the floor and proclaims himself a fraud, quietly sobbing to himself. Then he screams that he's a monster and the episode ends with [[JumpScare a mass of pink spikes bursting out of his back.]]

* ''WesternAnimation/LooneyTunes'': WesternAnimation/DaffyDuck seems to fall victim to this a lot. A perfect example occurs in ''Duck! Rabbit! Duck!'' after he gets shot by Elmer Fudd one too many times:

** A year earlier, Daffy Duck himself tells how he did quite well working on a merry-go-round until it broke down.

** In ''WesternAnimation/PorkyInEgypt'', Porky's camel succumbs to "desert madness" and has a FreakOut that alternates between hilarious and genuinely unnerving.

** Old Man [=McGucket=] [[spoiler: helped build the machine in Stan's basement thirty years ago, but an accident with the device heavily traumatized him. He then built a gun that would erase the memory from his mind, creating the Society of the Blind Eye so that others wouldn't be freaked out or traumatized by the weirdness of Gravity Falls. However, repeated use of the memory wipe took a toll on [=McGucket's=] sanity, until he was reduced to the junkyard dwelling town kook he is today.]]

* Rigby of ''WesternAnimation/RegularShow'' goes cuckoo when he learns the "Death Punch of Death", to the point where he's willing to drown in lava if it means beating Mordecai at Punchie's.

** Frank Grimes learns the hard way in "[[Recap/TheSimpsonsS8E23HomersEnemy Homer's Enemy]]" that being the OnlySaneMan in a CrapsackWorld is not conducive to one's long term health.

** Homer again in "[[Recap/TheSimpsonsS10E13HomerToTheMax Homer to the Max]]". When the whole town pesters Homer for sharing a name with a new, buffoonish TV character, he begins going crazy with paranoia.

** "1%" ends with the implication that Cartman's sociopathic tendencies are growing into a full blown psychosis.
*** Even without any greater implications, you can see his sanity suffer with each stuffed animal destroyed.

*** Randy’s SanitySlippage is a recurring arc throughout the series, with him going from a BumblingDad to a selfish ManChild, and finally the deranged, murderous [[CorruptCorporateExecutive head of a weed farm.]]

** Eddy loses it on a few occasions, such as in "Laugh Ed Laugh" when all the Kids get chicken pox, leaving him with no one to scam.
** "Little Ed Blue" has Ed become massively pissed off for apparently no reason. [[spoiler: Turns out [[RampageFromANail he had a pebble in his shoe]]. This revelation drove Eddy crazy too. ]] But when Eddy slaps him in an attempt to snap him out of it, Ed goes into a unstoppable rampage, eating metal slides and nearly snapping [[CompanionCube Plank]] in half.
** Kevin starts going manic from paranioa when the Eds go missing in "No See Ed."
** Rolf goes ballistic when he thinks [[ItMakesSenseInContext Ed has affiliated himself with wolves]] in "No Speak Da Ed."
** Edd goes insane in "Cleanliness Is Next to Ed-ness" from not being able to take a shower after his parents begin renovating theirs.

** "Little Ed Blue" has Ed become massively pissed off for apparently no reason. [[spoiler: He had a pebble in his shoe. This revelation drove Eddy crazy too. ]] But when Eddy slaps him in an attempt to snap him out of it, Ed goes into a unstoppable rampage, eating metal slides and nearly snapping [[CompanionCube Plank]] in half.

* ''WesternAnimation/MyLittlePonyFriendshipIsMagic'': "Cutie Mark Failure Insanity Syndrome" -- a pony failing to live up to their special talent (symbolized by their cutie mark) is the most common cause of ponies going nuts. (It's worth pointing out that in all of these cases, the insanity was cleared up by the end of the episode with ThePowerOfFriendship.)%% NOTE TO EDITORS: Please leave the mention of the fandom term for searchability.

* ''WesternAnimation/MyLittlePonyFriendshipIsMagic'': The FanNickname for this is "Cutie Mark Failure Insanity Syndrome", given that a pony failing to live up to their special talent (symbolized by their cutie mark) is the most common cause of ponies going nuts. (It's worth pointing out that in all of these cases, the insanity was cleared up by the end of the episode with ThePowerOfFriendship.)%% NOTE TO EDITORS: Please leave the mention of the fandom term for searchability.