Spiders used to terrify psychiatrist Russell Green.
He recalls one incident, involving a colleague, which led him to flee his workplace.
"Her son had tarantulas and she'd brought in the skin that one had shed," Dr Green explains.
"I just happened to be passing through the entrance to the hospital and she had it in a sandwich box.
"I immediately saw it and recognised it as a tarantula and tried to run out of the hospital."
Dr Green's arachnophobia - the exaggerated fear of spiders - is so severe that even a picture of one is enough to scare him.Augmented-reality arachnidsBut he has now co-developed Phobia Free, an app designed to help others with the same problem.
It uses a technique called systematic desensitisation- a method of slowly exposing sufferers to the object of their phobia.
Users first play a series of games with cartoon spiders, which start out as cute and harmless-looking but gradually become more realistic.
One early task involves helping a spider hide in a slipper while someone is using a vacuum cleaner.
Later players have to help calm down and help an injured tarantula, before finally being presented with a graphic version of the creature superimposed over a real-life view, created using augmented reality.
Continue reading the main story Dr Green's co-founder and fellow psychiatrist Andres Fonseca believes self-help can be hard as it requires willpower and motivation."We are hoping to get that magic bit of motivation that you get from games, where people will play them for hours and hours, and use that to get people to complete their treatment," Dr Fonseca says.
They are now working on Agoraphobia Free for people scared of situations that are hard to escape from.
Catch your breath Other developers are trying to use games for a different type of anxiety disorder, panic attacks.Computer programmer Simon Fox didn't know what was happening when he experienced his first panic attack six years ago.
He excused himself to a quiet room during a New Year's party after feeling anxious.
"I felt as though I couldn't breathe," he says.
What made the 30-minute-long attack worse, he recalls, was that he became worried he might have stopped breathing, which only increased his anxiety,
"I just thought I was dying basically," he adds.
Mr Fox experienced daily attacks over the next few months before seeing a psychiatrist, who taught him coping techniques including breathing exercises.
Now he is creating Flowy, a game that aims to teach others how to avoid hyperventilation.
Flowy aims to teach breathing exercises that can be used to combat panic attacks He intends to teach users to engage in diaphragmatic deep-breathing, using the large muscle between their chest and the abdomen.
To train them, the app will use puzzles involving kittens and robots, which they are instructed to play touching the screen when they inhale and releasing when they exhale. The idea is that the data can also be used to provide feedback, which can be shared with a doctor.
The software is due to undergo clinical evaluation in a few weeks' time.
Mr Fox suggests it could prove more effective than traditional breathing exercises during an attack.
"They're effective but difficult to stick to when you're in that state," he says.
Human touchHowever some experts, including analytical psychologist Elizabeth Gray, warn that even if these apps prove effective alongside more traditional forms of therapy, they should not be a viewed as a replacement for it.
Some psychologists are concerned by the idea of anti-anxiety apps being used as a standalone treatment "Without the therapy I don't think the anxiety is cured," she explains.
She adds that phobias should be overcome by identifying and analysing their underlying causes, adding that this requires a trained therapist.
"Therapy is about human relationships," Mrs Gray says. "I think in every therapist's view that's what cures.
"Apps are not a substitute for human relationships."
Close relationshipEven so, some believe the close relationship many of us have with our mobile devices gives them anti-anxiety potential.
Psychologist Phil Topham is a research fellow at the University of Western England. He led the team that developed Sam, the "self-help for anxiety management" app.
It offers self-treatment advice, allows users to log their mental and physical states on a variety of screens, and lets them share their experiences anonymously using its "social cloud" feature.
"People get very attached to their phones and their tablets," says Dr Topham, adding that this sense of familiarity can lead sufferers to trust their smart devices with conditions they might not want to share with friends or family.
The Sam app is designed to help users monitor and manage feelings of anxiety "There's quite a lot of shame attached to anxiety, in not being able to cope," he says.
"A mobile device is actually a very private device. You're not exposing your anxiety."
But while Dr Topham says the software can be used without the support of a registered health practitioner, he still advises potential users to consult an expert if they have any uncertainties.
