直到最近，人们曾以为人类的大脑在幼儿时期结束时就完全停止发育了。然而，在过去的十年间，有研究表明人类的大脑从青春期开始到成年初期的这段时间内仍然在变化。

What were you like as a teenager? I was a nightmare. I was rude to my parents, always stayed out late, never did my homework, hung out with the wrong people and made lots of bad decisions. Apparently, this is the age when teenagers are out of control and behave badly. Maybe, if you're a teenager now, you think this is unfair criticism or it's not your fault. Well, you might be right!

Experts have found that it's a teenager's brain that is to blame. Between the ages of approximately 13 to 19 - a period known as adolescence - the brain is still developing in areas that control behaviour. This has an impact on learning and multitasking, stress and memory, sleep, addiction, and decision-making. For parents, these consequences often manifest themselves in a variety of behaviours that they may have previously blamed on hormones or just moodiness.

This is quite a new discovery, according to Professor Sarah-Jayne Blakemore, who, speaking on the BBC radio programme The Life Scientific, says "when I was at university, the dogma in the text books was that the vast majority of brain development goes on in the first few years of life and nothing much changes after mid-childhood. That dogma is completely false."

So our brains are still developing much later than was originally thought. Is this the perfect excuse for teenagers to lounge around and not get their homework done on time? Of course not! According to Professor Sarah-Jayne Blakemore, it's to do with our prefrontal cortex – that's the part of our brain right at the front, just behind the forehead. She says "it's involved in a whole range of very high-level cognitive tasks such as decision making and planning - we know that this region is undergoing very very large amounts of development during the adolescent years". This is the part of the brain critically involved in planning, and, for a teenager, this hasn't developed yet. So getting organised to do their homework, for example, can come as a bit of a challenge.

I wish I'd known about this because instead of telling my teacher I'd left my homework on the bus or that the dog had eaten it. Now I could say, "Sorry sir, my brain isn't developed enough for the cognitive task of planning my homework".