I surrender: I have reached overload, the point where my online, virtual life is taking up so much time that it is affecting what I do in the physical world. Where yesterday I thought that internet connectivity was essential for everyday living, I now realise that it is merely a tool to make things easier, just like a rice cooker or an Octopus card. My face-to-face relationships are suffering, I am forgetting what the voices of far-off relatives sound like and I am not getting enough sleep. It's time to pull back, moderate and make an effort to shut down and unplug.

This appears to be an epiphany, but it has in reality been creeping up, a realisation not willingly accepted. It literally took a bump in the night to make me come to my senses. While crossing the street one evening last week, a man glued to the screen of his smartphone veered into my path and we collided. In the moments before the light changed and the traffic roared our way, he mumbled an apology that he should have been paying attention rather than chatting on Facebook.

He was far from being the only one so engrossed; all around are similarly connected people, their virtual lives making them forget where they are and what they are doing. Although I was not at fault, I only too well understand what it is like to be in front of a screen learning, being informed, entertained or catching up. Too frequently, I have gone off on a tangent, taking in things that I did not need to know or learning how to use something that in a year or two became obsolete. It makes a lie of the adage that knowledge is power; if we do not carefully filter online activities, it can simply be wasting time.

Dr Gary Small, a brain researcher at the University of California, Los Angeles, has also found it is mind-altering. In a study published in the American Journal of Geriatric Psychiatry, he showed that the frequent users of handheld devices with internet capability had twice as much brain activity as those of novices. The excitement of getting an e-mail alert released dopamine, a neurotransmitter that reinforced behaviour, fuelling a craving for more such stimulus. It's akin to drug addiction.