The hours spent hunched over mobile phone screens each day are causing an "epidemic" of bad posture and putting us at risk of serious back problems, according to a new study reports The Week

People now spend an average of four hours each day with their necks bent at an unnatural angle, which is putting pressure on their spines, according to a report due to be published in Surgical Technology International.

The research, by Dr Kenneth Hansraj, chief of spine surgery at New York Spine Surgery and Rehabilitation Medicine, found that pressure on the spine increases dramatically when the head is bent at a 60 degree angle.

The average adult head weighs around 10 to 12 pounds when it is upright, he says, but tilting it forward by just 15 degrees puts 27 pounds of pressure on the cervical spine, the portion of the spine above the shoulders. At 60 degrees this increases to 60 pounds.

"The weight seen by the spine dramatically increases when flexing the head forward at varying degrees," says the study. "Loss of the natural curve of the cervical spine leads to incrementally increased stresses about the cervical spine. These stresses may lead to early wear, tear, degeneration and possibly surgeries."

Bad posture has been linked to a host of medical problems, including headaches, neurological problems and depression, says CBS News, while good posture can elevate testosterone and serotonin in the body and reduce levels of the stress hormone cortisol.

"While it is nearly impossible to avoid the technologies that cause these issues, individuals should make an effort to look at their phones with a neutral spine and to avoid spending hours each day hunched over," says the study.

Last year, research by healthcare provider Simplyhealth found that 84 per cent of people aged 18 to 24 had suffered back pain in the last 12 months. It blamed the high level on "iPosture", the stooped body shape adopted by those texting, emailing or playing games on their iPad or smartphone.