Feeling a bit under the weather and can't work out what's causing it? Electromagnetic radiation from mobile phones, plasma screen televisions and computers could be the cause

Most of us own a large variety of electronic equipment, mainly because it makes life so much easier. Your laptop allows you to work and surf from home, your mobile means you're never out of touch, your cordless phone allows you to multi-task and a baby monitor lets you constantly check on your little one.

But have you ever stopped to think about all the invisible electromagnetic radiation, or 'electrosmog', resulting from the use of both wireless technology and mains electricity? Probably not, but a small group of people are convinced electromagnetic fields (EMFs) are the cause of their health problems.

Health practitioner Sue Donnelly, mum to William (both pictured above), began to have problems sleeping and suffered from frequent headaches. William suddenly became very hyperactive.

She says: 'I was beside myself with exhaustion, and confused as to what was happening to me when, as we drove down a road we don't often use, my son shouted out "mummy there's a huge new mast". It was on the college building about 400-500m from our house. It had been erected with no warning whatsoever from the council or the mobile phone company.

'This of course explained all my symptoms. I had previously checked my area and house with an Electrosmog Detector (a device that buzzes with static when it encounters electronic radiation) and there had been absolutely nothing affecting my house. We went home, and now the Electrosmog Detector was alive with the sounds of these new signals. I asked the council when the mast had been turned on and, of course, it was exactly the day William first became hyperactive and couldn't sleep.'

Sue continues: 'I have now taken the necessary steps to protect my son and my home and I'm lucky that at the moment this is the only mast near enough to affect us. I used shielding materials in the bedrooms and, practicing what I preach, we are taking the correct nutritional supplements. If we detect more signals in the future, I would consider getting a Schumann Frequency Generator (a magnetic pulse generator that mimics the earth's frequency - electrosmog drowns this natural frequency out) for the whole house, and shielded bed canopies (like mosquito nets) in order to ensure a good night's sleep.'

Sue's reaction may sound a little extreme, but electrosmog is thought to be responsible for a condition known as electrosensitivity (ES) or electrohypersensitivity (EHS). The symptoms include headaches, disruptive sleep patterns, chronic fatigue, depression, epilepsy, skin complaints and disruptive behavioural patterns in children. It is thought to affect between three and ten per cent of the world's population.

In Sweden, 285, 000 people (over three per cent of the population) are registered as ES sufferers and claim disability benefit from the government. In Germany, the bau-biologie movement helps people organise their own living and working places to minimise environmental hazards.

In the UK, ES is not an officially recognised condition and GPs are, on the whole, not familiar with the problem. The World Health Organisation in a statement drafted in December 2005 says, 'There is no scientific basis to link ES symptoms to EMF exposure. Further, ES is not a medical diagnosis, nor is it clear that it represents a single medical problem.'

Sarah Dacre is another sufferer who self-diagnosed ES after getting no answers from the health profession.

'Four years ago, I was fit, in my forties, with a dynamic marketing and media business, exciting social life and active sporting schedule. My lifestyle was exciting and affluent. I had energy and dynamism. Without noticing too much, I gradually succumbed to a host of symptoms which sapped my energy and stole my memory.

'I kept myself going and as insomnia, erratic high blood pressure and heart palpitations joined the list, I got nervous. I tried my doctor, various complimentary practitioners, a Chinese doctor and then, as I felt more and more unwell, I paid what seemed an enormous sum to visit a private 'doctor' on Harley Street. Not one of them told me what was wrong with me.'

Sarah now sleeps in a shielded room with foil-lined wallpaper. Her windows are screened with EMF-proof fabric, she wears a radiation-proof head net for car travel, takes numerous supplements and avoids all toxic environments. She has now joined a group of scientists, hese-UK, who assess human exposure to EMFs and pool and collate ES case studies from around the world.

Before you dismiss it, Sir William Stewart, the head of the UK Health Protection Agency and National Radiological Protection Board points out that our bodies are all unique and can take different stresses and strains. In a safety report to the Trade and Industry Select Committee Inquiry of Parliament, with regard specifically to mobile phone microwaves, he said 'it is simply not possible to say that there are no potential effects on the human population.'

Professor Lawrie Challis, one of the world's leading experts on mobile phone radiation and chair of the mobile telecommunications health research programme, seems in agreement.

Speaking to The Times, Professor Challis reveals that the first batch of research the programme has carried out confirms mobile phones are safe in the short-term (under ten years).

But there is some worrying news. 'It's encouraging because they found nothing for people who've used phones for less than ten years,' adds Challis. 'But there is a hint of something for people using them more.' Professor challis is currently trying to get funding for more research.

For more information on ES, visit www.electrosensitivity.org.uk and for electrosmog detectors, visit www.detect-protect.com