Long neglected by science, "middle childhood" between the age of six and 12 years old is a transformative period preparing children for growing up. Here's what's going on in their heads during this turbulent time plus how to navigate it.

My first small act of rebellion came when I was around six years old. I'd just been to a birthday party in the local village hall, with a bunch of children I barely knew. They'd all arrived with their friends, and I felt shy and left out.

By the time I returned home, I was in the foulest of moods. I don't remember what my mum asked me to do, but I can clearly recall my response. "It's alright for you, lazing about," I snapped, "while I had to go to that party!"

I then stormed off, leaving her speechless. What had happened to her sunny little boy?

She might have been less surprised if we had lived in German-speaking country. The word Wackelzahnpubertät – literally "wobbly-tooth puberty" – describes how six-year-olds start to show the bad moods characteristic of adolescence. "Aggressive behaviour, rebellious activism, and deep sadness are typical of the wobbly-tooth puberty," is how the German magazine Wunderkind puts it. (Read on to the bottom of this piece for some tips on how parents can deal with this change in behaviour.)

Unlike the real deal, wobbly-tooth puberty is not driven by hormonal changes. Instead, it coincides with the start of "middle childhood" – a period of profound psychological change in which the brain lays the foundations for more mature thoughts and feelings. "It is a really key stage in which a child is constructing their identity, and they're trying to figure out who they are in relation to other people," says Evelyn Antony, a doctoral student in psychology at Durham University in the UK. "And their emotional world is expanding as well."

Whereas infancy and adolescence are now well-understood, middle childhood – which spans ages six to 12 – has been sorely neglected in scientific research. Some psychologists go as far as to describe it as our "forgotten years". "A lot of the research focuses on the early years, when babies are talking and walking, and then in adolescence when you have a bit more of rebellion," says Antony. "But there's less known about middle childhood."

That is now changing, with new research identifying the core characteristics of children's mental metamorphosis. The transformation includes a greater capacity to reflect on their feelings and modify them when needed, along with an "advanced theory of mind" that allows them to think more sophisticatedly about others' behaviours and respond appropriately. They also begin master the basics of rational enquiry and logical deduction, so that they can take more responsibility for their actions – which is why, in France, it is also known as l'âge de raison.

As the concept of wobbly-tooth puberty illustrates, the onset of middle childhood may be accompanied by some growing pains, but a deeper understanding of the neurological and psychological changes involved is offering new insights on the best ways to support a child throughout the journey.

Let's begin with emotional regulation. By the start of middle childhood, most children will have already made some huge advances in their capacity to control their feelings. As a newborn, they were completely dependent on the adults around them to soothe their anguish, which is most often caused by physical stressors like hunger, fatigue, or colic. Over the next couple of years, they develop a greater emotional repertoire that includes joy as well as anger and fear, but they do not know how to regulate them – leading to those eardrum-exploding tantrums.

A child's burgeoning language can provide some relief from those maelstroms. That's partly because it allows the child to express their needs more precisely, so that others can respond appropriately before the frustration builds up. There is no need to scream when you want more food if you can simply say "I'm hungry", and a caring adult responds. Emotion words may bring an even more immediate benefit, however. Naming an emotion appears to change its neural response, engaging parts of the prefrontal cortex, which is an area involved in more abstract thought, while soothing the amygdala, the region involved in the sensation of the raw emotion.

As a child reaches five or six, however, they face new challenges that put their emotional understanding to the test, Antony and other researchers say. Rather than relying on adults to guide their........

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