A 13-year-old schoolboy with autism fled from his classroom in fear after being shown a frightening shower scene from Alfred Hitchcock's 15-certificate film Psycho.
Dougie Parr ran to the toilets and vomited after being shown the clip in a music lesson by his teacher at Comberton Village College in Cambridge.
The school were forced to apologise after showing the famous footage to a class of Year 9 pupils to demonstrate the power of music in creating feeling.
Terrified: Schoolboy Dougie Parr, 13, fled the classroom in terror and vomited after being shown the famous shower scene from the film Psycho. His mother Kate Bourne, 40, said he couldn't sleep afterwards
Famous scene: Janet Leigh screams in terror in Alfred Hitchcock's 15-certificate film. A 13-year-old boy was terrified after seeing it in school
In the scene actress Janet Leigh is stabbed through a shower curtain to the sound of screeching violins but the actual murder is not shown.
Dougie's mother Kate Bourne, 40, said he was so upset he struggled to eat and sleep when he got home and needed reassurance that no-one was going to hurt him.
She is angry that the school showed the 15-certificate film on Monday without seeking parental consent.
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She has now had a personal apology from the teacher involved and the school has promised to 'review' the lesson.
Kate, a mother-of-three from Cambridge, said: 'Dougie came flying through the door after school saying, "I had to watch the bloody shower scene from Psycho in music".
'His teaching assistant had written in his homework diary that Dougie had been so upset by the film he had left the classroom and been sick in the toilet.
Film stars: Janet Leigh and John Gavin play Marion Crane and Sam Loomis in Alfred Hitchcock's classic film from 1960 Psycho
'Dougie said it felt like his heart was going to come out of his chest and he was going to have a heart attack. He was completely traumatised by the film.
'He wouldn't eat anything for dinner and couldn't get to sleep on Monday night. He was shaking all over. It was heartbreaking to see.
Director: Alfred Hitchcock on the set of Psycho
'I've had to repeatedly reassure him that no-one is going to come into the house and get him and that he is safe now.'
Kate, who describes her son as having mild autism, added: 'Dougie is quite sensitive to noises, so even if his teachers had just played the soundtrack it might have distressed him.
'Parents should be able to send their children to school without having to worry about what they will be shown.
'The school should have asked my permission to show my 13-year-old a certificate 15 film.
'The music teacher said the film was shown to demonstrate the impact music can have to create feeling and said there is no other film scene which would give the same depth of feeling.
'But I completely disagree - they could have used Jaws and that's only a certificate PG.'
Kate said: 'I'm happy to accept the teacher's apology and delighted that he said he would change his teaching plan and not use the film again.
'But it feels a bit like shutting the stable door after the horse has bolted.'
Dougie said: 'It was a really horrible experience.
'I just had to get out of the classroom. I was boiling hot and I thought I was going to be sick.
'I don't think the teacher should have shown me the film.'
The school said it was 'very regrettable' that Dougie found the film distressing.
In an email to Kate the music teacher said he had been showing the film to classes for six years without negative feedback but it would not be used again.
Fear: Douglas Parr, 13, pictured with his mother Kate, was shown the footage from Psycho during a school music lesson
Film scene: The schoolboy was shown the frightening clip at Comberton Village College in Cambridge
He said he got the idea from a teacher training course more than a decade ago.
Peter Law, one of the school's head teachers, said: 'The scene was explained to pupils before being shown, and afterwards it was evaluated to look particularly at how the music was integral to the mood.
'This particular lesson is one that the teacher was first shown on a music teacher training course over a decade ago, and has been used many times with different classes.
'It is very regrettable that a pupil found this distressing, and a full apology and explanation has been given to the parent who highlighted this concern and will also be made to the pupil.
'We are now reviewing this particular scheme of work to ensure that we can continue to offer stimulating and challenging lessons without potentially causing upset to any pupils.'
The British Board of Film Classification advises schools to seek parental consent before screening films to children under the legal age.
Remake: Scarlett Johansson playing Janet Leigh in a 2012 recreation of the classic shower scene in Psycho