A gentle rub of the head has long been used by parents to soothe children.
Researchers have found that some nerves in the skin send 'feel good' signals to the brain when activated by just the right amount of stroking. he 'C fibre' nerves usually transmit messages of pain but record pleasure when the skin is stroked at about four centimetres per second, according to the study carried out by scientists in Britain, Germany and the United States and is published in the journal, Nature Neuroscience.
Researchers demonstrated the effect of C-fibres on volunteers using a 'robotic tactile stimulator' – a mechanical arm fitted with soft brush. Sensually caressed by the robot, the volunteers produced C-fibre signals that could be recorded.