Jerusalem is a city that conjures up a sense of the holy, the historical and heavenly. The biblical city has been a magnet for pilgrims devoted to several of the world's faiths and religions, notably Jews, Christians and Muslims. Millions flock to the ancient, religious city every year. But for a small percentage, their excitement induced by their close proximity to  holy landmarks invokes a rare condition known as Jerusalem syndrome. First identified in 2000,  psychologists noted religious pilgrims overcome with excitement at being in close proximity to the city's holy places believed they were Biblical characters. It is characterised by anxiety, agitation and nervousness. And sufferers are often consumed by a need to be clean, before donning a toga-like gown often made from hotel bed linen. Jerusalem syndrome affects people visiting the holy city. It is characterised by seven stages, including anxiety, the need to be clean and performing sermons . The next stage sees sufferers overcome by the need to scream, or sing out loud psalms, verses from the Bible, religious hymns or spirituals. A procession or march to one of the city's holy places, is then finally followed by the delivery of a 'sermon'. The condition, which was first reported in 2000, often affects people with no history of mental health problems, LiveScience reports. However, in many other cases, experts believe the condition is likely part of a broader psychosis, that is not unique to Jerusalem. Simon Rego, director of psychology training at the Albert Einstein College of Medicine/Montefiore Medical Centre in New York, told LiveScience: 'You see things like this emerge periodically in the literature, where people think they have found a unique syndrome.' But, he said, it may simply be the result of an underlying mental illness. A study, published in the British Journal of Psychiatry, noted that since 1980, Jerusalem's psychiatrists had encountered an ever-increasing number of tourists who, upon arriving in the city 'suffer psychotic decompensation'. A study published in the British Journal of Psychology identified seven sequential stages of Jerusalem syndrome: . 1. Anxiety, agitation, nervousness and tension, and other unspecified reactions. 2. Declaration of the desire to split away from the group or the family and to tour Jerusalem alone. Tourist guides aware of the Jerusalem syndrome and of the significance of such declarations may at this point refer the tourist to our institution for psychiatric evaluation in an attempt to pre-empt the subsequent stages of the syndrome. 3. A need to be clean and pure, an obsession with taking baths and showers and compulsive fingernail and toenail cutting. 4. Preparation, often with the aid of hotel bed linen, of a long, ankle-length, togalike gown, which is always white. 5. The need to scream, shout, or sing out loud psalms, verses from the Bible, religious hymns or spirituals. Manifestations of this type serve as a warning to hotel personnel and tourist guides, who should then attempt to have the tourist taken for professional treatment. Failing this, the two last stages will develop. 6. A procession or march to one of Jerusalem's holy places. 7. Delivery of a ‘sermon’ in a holy place. The sermon is usually very confused and based on an unrealistic plea to humankind to adopt a more wholesome, moral, simple way of life. As a result of noting 'the consistently high incidence of this phenomenon', a decision was taken to channel all cases to one central facility - the Kfar Shaul Mental Health Centre. There patients received psychological counselling, psychiatric intervention and, if deemed necessary, admission to hospital. Over a 13-year period, from 1980 to 1993, 1,200 tourists with severe mental illness invoked by Jerusalem, were referred to the facility. Of these, 470 were admitted to hospital. On average, the study found 100 such tourists were seen by experts annually, with 40 a year requiring admission to hospital. Through the course of their study, the researchers identified three types of people affected by Jerusalem syndrome. The first included individuals already diagnosed as having a mental health illness before visiting Israel. Those patients were found to strongly identify with characters from the Old and New Testament. The study referenced one example of an American tourist suffering paranoid schizophrenia, who believed he was the biblical character Samson. He visited Israel because he was compelled to move one of the giant stone blocks forming the Western (Wailing) Wall which, in his opinion, was not in the right place. On arriving at the Western Wall, he attempted to move one of the stones. But his actions instigated a commotion, which resulted in his being admitted to the Kfar Shaul Mental Health Centre. The second group includes those people with personality disorders and obsessions with fixed ideas, but who do not have a clear mental illness. Researchers cited the case of a healthy German man who was obsessed with finding the 'true' religion, and travelled to Jerusalem to study Judaism. He ended up suffering a psychotic episode in the Church of the Holy Sepulchre, built on the site where Jesus is believed to have been crucified and buried. Three types of patient were identified, the first group being those with already underlying mental illness. One example was of an American tourist suffering paranoid schizophrenia, who believed he was the biblical character Samson. He visited Israel because he was compelled to move one of the giant stone blocks forming the Western (Wailing) Wall, pictured, which, in his opinion, was not in the right place . And the third type of patient, identified in the study, were those with no history of mental illness, but who experienced a psychotic episode while in the city. This group recovered spontaneously after leaving Israel. of the 1,200 patients examined, just 42 fell into the third category. Despite the study, the notion of Jerusalem has been condemned by a number of experts. Dr Alan Manevitz, of New York's Lenox Hill Hospital, told LiveScience he believes the condition may happen when a person who is at risk of psychosis experiences the stress of travelling to another country. 'I think what happens is, vulnerable people can be inspired by the circumstances around them,' he said. Dr Rego, agreed the condition may not be unique to Jerusalem. 'If it was purely causal, you would expect everybody who visits Jerusalem to get it,' he said.
Experts first identified the rare condition in 2000, noting seven symptoms.
Sufferers first appear anxious and agitated and are consumed by a need to be clean before donning a toga-like gown often made from bed linen.
They are then overcome by the need to scream verses from the Bible.
A procession to one of the city's holy places is followed by them delivering a 'sermon' in public.