Last weekend, the Wellcome Trust celebrated 75 years of medicine on screen by transforming the Truman Brewery into a 1980s hospital, complete with a therapy on film ward. Here, visitors were offered consultations with a "doctor" who prescribed a healthy dose of film to cure your malaise. I've long suspected the only effective treatment for the common cold is repeated doses of romcom to be applied on the sofa, but can film really make us feel better?

I perch on a blue plastic chair and thumb a genuine 80s copy of Smash Hits while waiting for the doctor. The walls are lined with ads expounding the dangers of smoking while pregnant (low birth rate) and of smoking before kissing (reduced likelihood of repeat kissing). Medical assessment form completed, I'm taken through to the ward.

Disappointingly, the doctor doesn't have anything to help clear up an eye infection that's bothered me recently. Instead, she offers me something to help cut down on booze. I'm settled into a hospital bed behind a green screen and given a pair of headphones. My prescription, a public health film featuring a group of twentysomethings getting pissed down the pub, begins.

First, a barmaid warns the group's ringleader that beer will make him fat. Then the girls in the group flounce off, repelled by his drunkenness. To me it looks like he's having a jolly time. And the girls seem like party poopers. Meanwhile, my friend Claire has been prescribed a clip with cartoon toes talking to each other about uncomfortable shoes intended to treat her shopaholism. Within minutes of leaving we're talking about frocks, so I think she probably needed a stronger dose.

Our treatments might have been ineffective, but can cinema more generally improve our health and wellbeing? In a roundabout way, film does affect our health. Movies like Michael Moore's Sicko and One of Them Is Named Brett (a documentary by the event's host, Roger Graef, on thalidomide children) can change attitudes and, eventually, government policy. Film can also inspire us to take better care of ourselves. What might have been "Oh, just a funny lump" could become "Oh, just a funny lump I must get checked out" after a couple of hours sobbing in front of Terms of Endearment. In the same way, film can be bad for you. Hollywood has long been like the cool kid at school your mum would prefer you didn't hang out with. It smoked, so we smoked. It starved itself to a size 0, so we developed an unhealthy body image. It didn't wear a seatbelt in high-speed car chases, so we didn't wear one when popping out for milk.

But film can act as an emotional balm. Lorenzo's Oil might help a parent come to terms with having a sick child. The Lost Weekend has helped people understand alcoholism. My Left Foot has potential to help someone overcome a disability. The Men, in which Marlon Brando played a war veteran paralysed below the waist, inspired many disabled veterans to live fuller lives. Film can show us that we are not alone in our experiences. Consider the story of Norman Cousins, a journalist who prescribed himself Groucho Marx films in order to induce the anaesthetic effect of belly-laughter. That alone makes me feel better.

In 2005, researchers at the University of Maryland school of medicine compared the effects of watching the first 15 minutes of Saving Private Ryan to watching 15 minutes of Kingpin. They concluded that comedy is brilliant for the vascular system. If you're the kind of person who gets grouchy when denied a weekly trip to the cinema, there could be a genuine medical reason. Graef points out that film is "like a kind of active meditation". Meditation has been found to lower blood pressure, aid relaxation, improve concentration and even slow down brain deterioration due to ageing. Regular practitioners report feeling irritable and depressed if forced to go without. If watching a film really is like meditating, that could be why you get prickly when denied it.

But what of my trip to therapy on film? Did it make me feel better? Well no, not really. Perhaps a public health film wasn't the best way to go. It just made me fancy a trip down the pub …

• Therapy on film was part of Just What the Doctor Ordered: 75 years of Medicine on Screen. Therapy on film's clips were drawn from the Wellcome Collection's moving image archive.