Nomophobia is the fear of being out of mobile phone contact - and it's the plague of our 24/7 age

But it seems they are now matched by a new, peculiarly 21st century affliction - the fear of being out of mobile phone contact.

Millions apparently suffer from "no mobile phobia" which has been given the name nomophobia.

They have become so dependent on their mobile that discovering it is out of charge or simply misplacing it sends stress levels soaring.

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More than 13million Britons fear being out of mobile phone contact, according to research.

Keeping in touch with friends or family is the main reason why they are so wedded to their mobile.

More than one in two said this is why they never switch it off.

One in ten said they needed to be contactable at all times because of their jobs, while 9 per cent said that having their phone switched off made them anxious.

Experts say nomophobia could affect up to 53 per cent of mobile phone users, with 48 per cent of women and 58 per cent of men questioned admitting to experiencing feelings of anxiety when they run out of battery or credit, lose their phone or have no network coverage.

The Post Office questioned more than 2,100 mobile phone users. Stewart Fox-Mills, the company's telecom expert, said: "Nomophobia is all too real for many people.

"We're all familiar with the stressful situations of everyday life such as moving house, break-ups and organising a family Christmas.

"But it seems that being out of mobile contact may be the 21st century's latest contribution to our already hectic lives.

"Whether you have run out of credit or battery, lose your phone or are in an area with no reception, being phoneless can bring on a panicky symptom in our 24/7 culture."

Researchers advise those keen to avoid nomophobia to keep their credit topped up, carry a charger at all times, give family and friends an alternative contact number and carry a pre-paid phonecard to make emergency calls if your mobile is broken, lost or stolen.

Other tips include keeping a record of your numbers in case you lose your handset and carrying the phone in a closed pocket or bag to avoid loss or theft.

They add that you could also try to liberate yourself from the shackles of your mobile by simply switching it off.