Jane has now been diagnosed as suffering with obsessive compulsive disorder (OCD) and is one of a growing number of children being treated for a condition that is more commonly associated with adults.
Britain's first clinic for young sufferers of OCD, at The Maudsley Hospital and the Institute of Psychiatry, has recently started seeing patients. They can be as young as seven, with a range of distressing symptoms including hand-washing rituals that take up as much as seven hours every day.
Although OCD remains a hidden and secret disorder among children, new research shows that as many as one per cent of all children, or around 45,000 in Britain, may suffer at any one time. It also found that the problems for many adults with OCD began when they were as young as four or five.
OCD is defined as recurrent obsessions or compulsions which are severe enough to cause distress and interfere with normal life. Obsessions are persistent ideas, thoughts or images, while compulsions are the repetitive behaviour that is performed as a result.
"Many children have mild obsessions and compulsions at some time. Some, for example, may organise their books or toys in a certain way. It is only when the ritual distresses the child, or interferes with normal life, that we need to look for signs of OCD,'' says Dr Isobel Heyman, a clinical lecturer in child psychiatry at the Institute of Psychiatry, whose clinic has so far assessed around 70 children.
"This distress is often hidden because children see their symptoms as peculiar or embarrassing, and keep them secret, sometimes for years.''
In an attempt to raise awareness of the condition, the hospital is developing a unique interactive CD-Rom package designed to help young people and their families, as well as other health professionals.
Although OCD has been recognised as a disorder for many years, the causes are not fully understood. It was once considered to be a reaction in early childhood to being potty trained too young, or to having over-perfectionist parents, but there has been no real scientific evidence for either theory.
The evidence now favours a significant genetic input, because those who have OCD are 10 times more likely to have a parent or a sibling with the disorder.
It is also known that sufferers have an imbalance of serotonin, a neuro- transmitter chemical in the brain involved in a wide range of activities in the body.
One of the latest theories is that the recurrent obsessive thought and the compulsive action may be something that just happens, like a nervous tic.
"Just as a muscle moves itself because the brain makes it happen, a thought or complex action may be generated like a tic in the mind. But we then try to rationalize what we are doing. As a consequence, if you find yourself washing your hands repeatedly, you make the wrong assumption you are doing it because you must be dirty,'' says Dr Heyman.
Whatever the causes, the effects can be both baffling and bizarre, as well as being very upsetting for both child and parents. "One of the most extreme cases was a girl who had a seven-hour washing ritual which filled up her whole day, and if something went wrong in the order she was doing it, she had to start all over again. It occupied her whole life,'' says Dr Heyman.
"Then there are children who have what we call `evening-up' rituals. In one case, a boy who touched something with one foot had to touch it with the other. If he moved one foot and bumped into something he had to even it up by doing it with the other.
"The youngest we have had was seven, but some of the older children's parents have told us that they were ritualistic as young as four or five. Around 70 per cent of adults with OCD say their symptoms started in childhood.''
One mother, whose son Stephen has been successfully treated for OCD by Dr Heyman, describes the kind of distressing symptoms that can last sometimes for some years. "The problem my son had was that he did not want to sit down - he would stand up all the time, and he didn't like being touched. He thought things like chairs were dirty and that things around him were dirty.
"He would watch TV standing up and, if we did manage to get him outside, he would never walk with us, it was either in front or behind looking around all the time to make sure he wasn't touching anything. It was very distressing.''
There are two principle types of treatment for OCD - medication and behaviour therapy. Medication, which can be used alone or with behaviour therapy, involves drugs which act on the brain chemical serotonin. A wide range of these drugs are on now the market, including Prozac.
Research suggests that at least 70 per cent of OCD sufferers will get better with medication. Drugs can also achieve a quicker response than other forms of therapy.
In treating OCD, behaviour therapy involves taking a detailed assessment of the problem, often starting with the child and family keeping a diary of the obsessions and compulsions. The therapy is aimed as teaching the child how to control the problem, and around 80 per cent of sufferers recover.
One of the reasons why children carry out the compulsions is because of anxiety about what will happen should they stop. One of the ways of tacking OCD is to help the child learn how to deal with this anxiety, by letting them see that nothing untoward does happen if they delay their washing or counting or checking.
For Jane and her family, behaviour therapy was the key to her successful treatment. She told therapists that she felt she had to go through her ritual or something awful would happen. The key to her therapy was to persuade her that this would not be the case. So each night, her mother reduced the number of times she said goodnight and now it's down to just three.
To the outsider, these may seem like small changes in behaviour, but for Jane and children like her, the therapy is the key to regaining a young life, free of abnormal anxiety and distress.