Up and down the country, thousands of four-year-olds are enduring long, dark nights of the soul. They’ve just had their first taste of Big School, and in any cases the strain is starting to show.

In many schools, come nine in the morning in the Reception classroom, there is an ungodly chorus of anguished crying. Sometimes, even the parents are at it. Over the weekends, in the parks, streets and cafes of Britain, little wan faces can be seen.

It is the moment of separation that comprises the biggest trauma. For a parent, saying goodbye and walking away while your child is crying its little heart out is the most counter-intuitive thing imaginable. Throughout the day that follows, the conflict between head and heart rages.

In 1970, the Canadian psychologist Margaret Ainswoth published a landmark study known as the “Strange Situation Classification”. It involved observing – through a one-way glass – the way in which different one-year-olds responded when their mother left the room, and a stranger returned in her place. The study concluded that that the psychological health of a child, and its ability to deal with and explore new situations, depended on the extent to which it had already developed a secure bond with its “attachment figure”, usually the mother. “Securely attached” children view themselves as worthy of respect, and others as essentially benign. Insecure “avoidant” or “resistant” children, however, might suffer from a negative self-image, causing them to respond to the world in a negative or volatile way.

Sue Gerhardt, the British psychotherapist, modernised this idea by supporting it with neuroscience. In her 2004 book Why Love Matters, she argued that since babies are unable to come up with appropriate stress responses by themselves, the style of care they receive determine the basis of their future character. Neglecting baby’s needs leaves a biochemical imprint on its brain; repeated stressful experiences lead to the over-production of a hormone called cortisol, which can lead to damage being done to the brain’s regulation mechanism. The over-production of cortisol may result, leading to anxiety and depression. Alternatively, the brain may try to compensate and produce insufficient levels of the chemical, causing a lack of empathy and aggressiveness. Read on the Telegraph website