Early screen viewing is likely to lead to long periods of viewing for the rest of your life," says Sigman. "The way you view screens when you are young forms the habits you pick up for ever after it seems.”
An early taste for entertainment screen media can lead to changes in the brain that stay with you for life – a life that may be shorter as a result.
Like other addictions screen time creates significant changes in brain chemistry – most notably, in the release of dopamine. This neurotransmitter – also known as the pleasure chemical – is central to addictions from sugar to cocaine.
"Dopamine is produced when we see something that is interesting or new, but it also has a second function. Dopamine is also the neurochemical involved in most addictions – it's the reward chemical.
"There are concerns among neuroscientists that this dopamine being produced every single day for many years – through for example playing computer games – may change the reward circuitry in a child's brain and make them more dependent on screen media," warns Sigman.
(If you want to see some head-scratchingly weighty, early scientific research on computer games and dopamine release, check out this 1998 research paper from the Division of Neuroscience and Psychological Medicine, Imperial College School of Medicine.)
On the perils of too much screen time Sigman has investigated the extent to which time online may be displacing face-to-face contact, and that lack of social connection is associated with physiological changes, increased incidence of illness and higher premature mortality.??