Smartphone users tap their touch screens thousands of times per day and this could adversely affect the nerves in their hands and arms, a new study has found.

According to Turkish researchers, in 2012, 1.06 billion people were using smartphones. Just four years later, in 2016, this had doubled to 2.1 billion. Users touch their phone screens an average of 2,617 times per day, with heavy users tapping their screens 5,427 times. That is equivalent to two million taps per year.

The researchers set out to determine whether this activity could be having an effect on hand and arm nerves.

"The median nerve is the main nerve responsible for the muscle movements we execute while using smartphones. We know that frequent repetition of certain movements can result in carpal tunnel syndrome and wanted to find out whether smart phone use might have the same kind of effect," they explained.

They divided 62 people into three groups. One-third were given conventional mobile phones that did not have any computer functions, one-third were allowed moderate use of smartphones, while the remaining one-third were allowed heavy use of smartphones.

"It turned out that the use of a classic mobile phone rarely has negative effects on the sensory functions of the median nerve or on motor conduction. However, heavy use of a smartphone, for its part, can have an unfavourable effect on the median nerve," the researchers found.

In fact, heavy phone users scored much higher on a questionnaire that recorded complaints about the hand, arm and shoulder. They were also found to have poorer motor nerve conduction. The motor nerves are responsible for carrying nerve impulses from the brain or spinal cord to the muscles.

"Nerve conduction in the dominant hand among heavy users was about 12% less than for the hand subject to less strain," the researchers found.

In worst case scenarios, heavy users could develop carpal tunnel syndrome, which is the name given to a sensation of numbness, weakness, tingling and general discomfort in the area of the wrist and hand.

Details of these findings were presented at the Congress of the European Academy of Neurology in Amsterdam.