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0:00:04 > 0:00:06- We're all different.
0:00:07 > 0:00:09- We all live a life - that's unique to us.
0:00:10 > 0:00:12- From our first breath...
0:00:12 > 0:00:14- ..throughout our life...
0:00:15 > 0:00:16- ..we learn and change...
0:00:16 > 0:00:19- ..we learn and change...- - ..as we adapt to our surroundings.
0:00:20 > 0:00:22- I'm Dr Anwen Jones, - a Physiology lecturer...
0:00:22 > 0:00:25- ..at Cardiff Metropolitan - University.
0:00:26 > 0:00:31- I'm Dr Katie Hemer, a Bioarchaeology - specialist at Sheffield University.
0:00:32 > 0:00:36- We'll look at the key developmental - steps for body and brain...
0:00:37 > 0:00:41- ..as we grow, mature and welcome - new members to our midst.
0:00:42 > 0:00:46- In each programme, we focus - on a specific stage of our life.
0:00:47 > 0:00:50- This is our journey through life.
0:00:56 > 0:00:59- Teenage Years
0:01:03 > 0:01:09- Stereotypically, teenagers - are moody, lazy, rebellious...
0:01:09 > 0:01:12- ..and highly emotional.
0:01:16 > 0:01:20- They take crazy risks - and they feel misunderstood...
0:01:20 > 0:01:22- ..especially by their parents.
0:01:26 > 0:01:31- While they seek their independence, - the body develops and changes...
0:01:32 > 0:01:37- ..but the huge changes which happen - in the brain are less obvious.
0:01:41 > 0:01:43- These shed light...
0:01:44 > 0:01:48- ..on some of the stereotypical - teenage behaviour we see.
0:01:54 > 0:01:58- During adolescence, - the body undergoes a process...
0:01:58 > 0:02:03- ..which transforms its shape, size, - appearance and the way it functions.
0:02:04 > 0:02:06- This is what's known as puberty.
0:02:06 > 0:02:11- The hypothalamus in the brain sends - a signal to the pituitary gland...
0:02:12 > 0:02:15- ..to release hormones - into the bloodstream.
0:02:15 > 0:02:20- The ovaries release oestrogen and - the testicles release testosterone.
0:02:21 > 0:02:25- Testosterone triggers huge changes - in the male body.
0:02:25 > 0:02:28- The shoulders widen, - the chest deepens...
0:02:28 > 0:02:32- ..and over a stone - of additional muscle is produced.
0:02:32 > 0:02:36- A girl's pelvis and hips widen, - the breasts develop...
0:02:36 > 0:02:39- ..and fat is stored - on the hips and bottom...
0:02:40 > 0:02:42- ..creating the female shape.
0:02:42 > 0:02:47- The ovaries start to release eggs, - as the menstrual cycle begins.
0:02:47 > 0:02:52- On average, puberty began at the age - of 17 around 150 years ago...
0:02:52 > 0:02:55- ..but it now starts much earlier, - at around 12.
0:02:55 > 0:03:00- Nobody knows why, but improved diet - is thought to be a factor.
0:03:04 > 0:03:07- The brain develops - throughout our teenage years.
0:03:08 > 0:03:13- How does this affect the way we - react to the world during that time?
0:03:14 > 0:03:18- With help from some Year 10 - volunteers at Ysgol Plasmawr...
0:03:19 > 0:03:22- ..educational psychologist, - Dr Rosanna Stenner...
0:03:23 > 0:03:28- ..runs an experiment to show how - the teenage brain sees the world.
0:03:29 > 0:03:31- Rosanna shows the pupils - some pictures...
0:03:32 > 0:03:36- ..with each person in the photos - displaying a different emotion.
0:03:36 > 0:03:41- The pupils note which emotion - they see in the photograph.
0:03:41 > 0:03:44- Show them to me now.
0:03:45 > 0:03:48- Almost all the pupils agree - on some of the faces...
0:03:49 > 0:03:51- What emotion - do you see on this face?
0:03:54 > 0:03:56- ..but others draw a mixed response.
0:03:57 > 0:04:01- What does this tell us - about the way we process emotions?
0:04:01 > 0:04:05- Today's experiment - may not have been very scientific...
0:04:05 > 0:04:08- ..but it did show us - huge differences...
0:04:09 > 0:04:11- ..in pupils' reaction to the photos.
0:04:12 > 0:04:16- These youngsters aren't always - certain what emotion they see...
0:04:17 > 0:04:20- ..although some photos - drew an unanimous reaction.
0:04:21 > 0:04:25- On the whole, everyone recognized - sadness and joy.
0:04:26 > 0:04:30- Some of them struggled - to recognize annoyance or anger.
0:04:32 > 0:04:35- Yes, many of them - found it difficult.
0:04:35 > 0:04:39- This uncertainty must have - a huge impact on teenagers.
0:04:39 > 0:04:44- Imagine a teenager seeing an adult - whose face is full of anger...
0:04:45 > 0:04:49- ..but that youngster - interprets it as a nervous look...
0:04:49 > 0:04:54- ..they'll react in a surprising way, - from the adult's perspective.
0:04:54 > 0:05:00- If they misinterpret the emotions - of people in their social circle...
0:05:01 > 0:05:04- ..it can rapidly - lead to difficulties.
0:05:04 > 0:05:08- In similar research, - teenagers and adults...
0:05:08 > 0:05:12- ..looked at photos of faces - whilst in an MRI scanner...
0:05:13 > 0:05:18- ..to see which part of the brain - processes emotion on people's faces.
0:05:18 > 0:05:23- Scientists found that teenagers and - adults process faces differently.
0:05:24 > 0:05:28- Teenagers use a brain structure - called the amygdala...
0:05:28 > 0:05:34- ..but adults use a section of the - brain called the prefrontal cortex.
0:05:34 > 0:05:37- The amygdala, - which is deep in the brain...
0:05:38 > 0:05:42- ..plays a vital part in processing - and reading emotion in others.
0:05:42 > 0:05:46- The prefrontal cortex, - in the front of the brain...
0:05:46 > 0:05:51- ..is in charge of decision-making - and controlling one's behaviour.
0:05:51 > 0:05:56- It does this by communicating with - different areas of the brain...
0:05:56 > 0:05:58- ..including the amygdala.
0:05:59 > 0:06:02- The prefrontal cortex - is like an orchestra conductor.
0:06:02 > 0:06:06- Teenagers go straight - to the amygdala...
0:06:06 > 0:06:08- ..bypassing the prefrontal cortex.
0:06:09 > 0:06:12- That means they may not - think about the emotions.
0:06:12 > 0:06:17- They're more reactive rather than - using more high-level processing...
0:06:17 > 0:06:20- ..which happens - in the prefrontal cortex.
0:06:21 > 0:06:25- You can think of the prefrontal - cortex as the brain's brakes.
0:06:25 > 0:06:30- It makes us stop and think about - probable outcomes of our actions.
0:06:30 > 0:06:33- Mature thinking - comes with experience.
0:06:33 > 0:06:37- You see the same thing - but process it differently.
0:06:37 > 0:06:42- Is this something we learn as we - move from adolescence to adulthood?
0:06:43 > 0:06:46- There are two elements - to this learning process.
0:06:47 > 0:06:51- Social experience and - experimentation with surroundings...
0:06:51 > 0:06:55- ..and, secondly, - the maturing reasoning processes.
0:06:56 > 0:07:01- We mature biologically and through - experience and experimentation.
0:07:02 > 0:07:06- How important is the ability - to read emotion in others?
0:07:07 > 0:07:12- You need that ability to become - empathetic and sympathetic.
0:07:13 > 0:07:18- Empathy and sympathy are vital - elements to any human relationship.
0:07:19 > 0:07:24- During adolescence, the brain - processes people's expressions...
0:07:25 > 0:07:28- ..in a different way - from the adult brain.
0:07:28 > 0:07:30- The prefrontal cortex...
0:07:30 > 0:07:34- ..which is vital to controlling - our actions as adults...
0:07:35 > 0:07:36- ..is still developing.
0:07:37 > 0:07:41- This may explain the teenage - tendency to be rash and emotional...
0:07:42 > 0:07:45- ..and to misunderstand others.
0:07:46 > 0:07:51- It may also explain another element - of teenage behaviour.
0:08:03 > 0:08:07- Adolescents are more likely - to do stupid things and take risks.
0:08:08 > 0:08:12- Why are teenagers more willing - to put themselves in danger?
0:08:12 > 0:08:14- Is it a conscious decision?
0:08:14 > 0:08:18- What happens in the brain to - make teens behave in this way?
0:08:25 > 0:08:29- James Williams has been racing cars - since he was ten years old.
0:08:30 > 0:08:34- He's now 17 and he hopes to become - a top-level rally driver.
0:08:34 > 0:08:37- He agreed - to take me for a spin in the car.
0:08:40 > 0:08:45- Many people would see rallying - as a dangerous, risky pursuit.
0:08:46 > 0:08:49- Would James agree with that?
0:08:50 > 0:08:53- What do you enjoy the most - about rally driving?
0:08:53 > 0:08:57- I enjoy the adrenaline rush - and the thrill of it.
0:08:58 > 0:09:00- I can feel my heart thumping.
0:09:01 > 0:09:02- What a feeling!
0:09:03 > 0:09:06- Do you see it as a dangerous sport?
0:09:06 > 0:09:07- Do you see it as a dangerous sport?- - No.
0:09:07 > 0:09:12- If you look at the car, you'll see - so many safety devices on it.
0:09:13 > 0:09:16- I don't think I'm taking a big risk.
0:09:16 > 0:09:18- Other people may disagree.
0:09:19 > 0:09:23- The risk is writing the car off - and having to pay for the repairs!
0:09:24 > 0:09:26- Like processing emotion...
0:09:26 > 0:09:30- ..it's believed we take - greater risks during adolescence...
0:09:30 > 0:09:33- ..because the brain - is still developing.
0:09:34 > 0:09:36- The brain's limbic system - plays a part.
0:09:37 > 0:09:40- The reward centre of the brain - is located here.
0:09:40 > 0:09:45- This makes us feel elation at - unexpectedly positive results...
0:09:45 > 0:09:49- ..such as winning a race - or being praised by our peers.
0:09:51 > 0:09:55- Risk taking and succeeding - also activates the reward centre.
0:09:55 > 0:09:58- Greater risk brings greater reward.
0:09:58 > 0:10:02- The limbic system is more sensitive - in our teenage years...
0:10:02 > 0:10:08- ..and the prefrontal cortex, which - controls behaviour and reasoning...
0:10:08 > 0:10:10- ..is still developing.
0:10:10 > 0:10:15- Do you think teenagers are more - likely to take risks than adults?
0:10:15 > 0:10:18- Some people my age - do take more risks...
0:10:19 > 0:10:21- ..and they don't see the dangers.
0:10:21 > 0:10:23- I'm not sure.
0:10:23 > 0:10:25- It depends on the person.
0:10:26 > 0:10:28- The prefrontal cortex...
0:10:28 > 0:10:33- ..which is so vital for planning, - judgement and impulse control...
0:10:34 > 0:10:37- ..doesn't mature fully - until our early 20s.
0:10:37 > 0:10:41- It may not be a coincidence - that teenagers take more risks.
0:10:43 > 0:10:46- During adolescence, - we start to explore our world...
0:10:47 > 0:10:50- ..and have new experiences - outside the home.
0:10:50 > 0:10:55- We yearn for independence and being - accepted by our peers is crucial.
0:10:56 > 0:10:59- As we get older, - sections of the brain...
0:10:59 > 0:11:04- ..which link memory and experience - with decision-making get stronger.
0:11:05 > 0:11:09- The more experience we have, - the more we can think rationally.
0:11:15 > 0:11:19- After the break, we discuss - challenges and sleep patterns...
0:11:20 > 0:11:24- ..as we look at more changes - which happen in the teenage body.
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0:11:33 > 0:11:38- Strange and unpleasant changes - happen in the teenager's body.
0:11:38 > 0:11:42- Clothes don't fit for long, - as we grow up to four inches a year.
0:11:43 > 0:11:48- This happens from the outside in, - starting with the hands and feet...
0:11:48 > 0:11:50- ..and in towards the spine.
0:11:51 > 0:11:53- Boys and girls' voices change...
0:11:54 > 0:11:59- ..but it's more obvious in boys, - when the voice breaks and deepens...
0:11:59 > 0:12:02- ..as the vocal cords - stretch and thicken.
0:12:02 > 0:12:07- It's hard to ignore the hair - which starts sprouting everywhere...
0:12:07 > 0:12:11- ..especially in the armpits - and below the waist.
0:12:11 > 0:12:14- Nobody knows - why we grow this hair...
0:12:14 > 0:12:16- ..but it may be - linked to attraction.
0:12:17 > 0:12:21- Some 80% of us suffer from acne - or spots during our adolescence.
0:12:21 > 0:12:26- Spots are created when we create - an excessive amount of sebum...
0:12:26 > 0:12:30- ..which usually - keeps the skin dry and healthy.
0:12:30 > 0:12:35- Sebum gathers under the skin and - traps bacteria, irritating the skin.
0:12:36 > 0:12:39- Children sweat - to control body temperature.
0:12:39 > 0:12:44- In our teenage years, we produce - a different kind of sweat...
0:12:44 > 0:12:46- ..in specific areas.
0:12:46 > 0:12:48- It's thick, greyish and oily.
0:12:48 > 0:12:53- When bacteria breaks this down, - it becomes smelly body odour, or BO.
0:12:55 > 0:12:59- Adolescence can be a difficult time.
0:13:00 > 0:13:04- I'm in Old Colwyn to hear all about - a Conwy Council scheme...
0:13:04 > 0:13:10- ..designed to help teenagers cope - with the challenges they face.
0:13:12 > 0:13:16- I want you to draw a picture - of a 14-year-old boy.
0:13:19 > 0:13:23- The scheme trains sixth form pupils - to become buddies...
0:13:24 > 0:13:28- ..and discuss sexual education - and teenage challenges...
0:13:29 > 0:13:31- ..with 13 and 14-year-old pupils.
0:13:31 > 0:13:36- Wendy Ostler, the scheme leader, - is holding a training session...
0:13:36 > 0:13:39- ..with the Ysgol Y Creuddyn buddies.
0:13:39 > 0:13:42- He's started to get some spots.
0:13:42 > 0:13:43- He's started to get some spots.- - And his voice is breaking.
0:13:44 > 0:13:47- Wendy, what's the aim of the scheme?
0:13:47 > 0:13:49- We give them three lessons.
0:13:50 > 0:13:52- One on making sensible decisions.
0:13:53 > 0:13:56- The second lesson - focuses on relationships.
0:13:57 > 0:14:02- The class lists 101 nice things - you can do with someone you love...
0:14:02 > 0:14:03- ..other than have sex.
0:14:05 > 0:14:08- The third lesson - is about keeping yourself safe.
0:14:08 > 0:14:13- Things like contraception and - safety when you use the internet.
0:14:13 > 0:14:17- Do children find it - easier to talk to young people...
0:14:17 > 0:14:19- ..who are closer to their own age?
0:14:20 > 0:14:25- Youngsters always say they'd prefer - to be taught about sex...
0:14:26 > 0:14:29- ..by youngsters who are - slightly older than themselves.
0:14:30 > 0:14:34- They find it easier than talking - to teachers or someone like me.
0:14:34 > 0:14:38- They don't think sex - had been invented when I was young!
0:14:39 > 0:14:42- I talked to the buddies - about the scheme...
0:14:43 > 0:14:47- ..and the challenges - faced by today's teenagers.
0:14:48 > 0:14:53- They know we went through the - same things when we were in Year 9.
0:14:54 > 0:14:58- We give them a chance - to ask things in confidence.
0:14:58 > 0:15:03- Things they want to know but they're - too embarrassed to ask in class.
0:15:03 > 0:15:05- We myth-bust for them too.
0:15:06 > 0:15:10- One of them had heard that - one form of contraception...
0:15:10 > 0:15:12- ..was to wear Crocs and socks.
0:15:13 > 0:15:17- Year 9 pupils want to think - they don't need any help...
0:15:17 > 0:15:19- ..and that they're independent.
0:15:20 > 0:15:23- They think they can live - however they think is right...
0:15:24 > 0:15:27- ..but that's not always - the right way to behave.
0:15:29 > 0:15:33- Does social media put a lot - of pressure on today's teenagers?
0:15:34 > 0:15:38- Yes, you see photos - on Facebook and Instagram...
0:15:38 > 0:15:41- ..and think, - "Whoa! I want to be like that."
0:15:42 > 0:15:44- Everything's based on looks.
0:15:44 > 0:15:47- Everybody's obsessed - with the way they look.
0:15:48 > 0:15:53- Yes, and that puts a lot of pressure - on young people to look good.
0:15:54 > 0:15:58- We need everyone to feel comfortable - during these sessions.
0:15:58 > 0:16:02- We try to teach them - that they don't need to change.
0:16:03 > 0:16:06- It's a period when - they want to push the boundaries...
0:16:07 > 0:16:10- ..but everyone around them - wants to keep them safe.
0:16:10 > 0:16:14- They need to learn to stay safe - before they take risks.
0:16:16 > 0:16:18- In the case - of some Year 9 students...
0:16:19 > 0:16:24- ..we're talking about situations - they won't encounter for years.
0:16:25 > 0:16:29- If someone learns something in maths - they won't use for two years...
0:16:30 > 0:16:33- ..nobody says it's too early - for them to learn about it.
0:16:34 > 0:16:39- Hormones and changes which happen - in the brain during adolescence...
0:16:39 > 0:16:42- ..have an unexpected impact - on the body.
0:16:43 > 0:16:46- We seem happy - to stay up until midnight...
0:16:46 > 0:16:50- ..and reluctant to get up - for school in the morning.
0:16:50 > 0:16:54- That's why many teenagers - are tired and irritable.
0:16:55 > 0:16:59- What are the biological reasons - for the shift in our sleep pattern?
0:17:00 > 0:17:04- To find out more, I talked to sleep - disorder expert, Dr Jose Thomas...
0:17:05 > 0:17:08- ..from the Aneurin Bevan - Sleep Centre.
0:17:08 > 0:17:10- This is Wales's only sleep centre.
0:17:11 > 0:17:16- The amount of sleep the teenager - requires for normal functioning...
0:17:16 > 0:17:20- ..is between eight and a half - and nine and a half hours.
0:17:20 > 0:17:24- If someone goes to bed at midnight - and they have to get up...
0:17:24 > 0:17:28- ..to go to school by half past seven - or eight o'clock...
0:17:29 > 0:17:33- ..they won't get eight and a half - to nine and a half hours' sleep.
0:17:33 > 0:17:36- They're chronically sleep deprived.
0:17:38 > 0:17:41- To take a closer look - at teenagers' sleep pattern...
0:17:41 > 0:17:44- ..we asked 14-year-old - Lowri and Elin...
0:17:45 > 0:17:47- ..to wear - a special tracker for five days.
0:17:48 > 0:17:52- The devices monitored - the girls' activity 24 hours a day.
0:17:53 > 0:17:55- This included - the time they were sleep.
0:17:56 > 0:18:00- The trackers - also monitored light levels.
0:18:00 > 0:18:03- Lowri wore her device - during the holidays...
0:18:04 > 0:18:07- ..and Elin wore hers - during term time.
0:18:08 > 0:18:12- The data collected by the devices - was then analyzed by Jose.
0:18:14 > 0:18:18- I met Lowri and Elin - to go through the results with them.
0:18:18 > 0:18:22- What did we discover - about their sleep patterns?
0:18:22 > 0:18:25- This is your data.
0:18:25 > 0:18:29- Elin, you go to bed - at between 9.30pm and 10.30pm.
0:18:29 > 0:18:32- On average, - you go to bed at 10 o'clock.
0:18:32 > 0:18:36- Lowri, the data shows - that bedtime for you...
0:18:36 > 0:18:40- ..is between 9.50pm and 12.50am!
0:18:41 > 0:18:44- On average, - you go to bed at midnight.
0:18:48 > 0:18:51- Let's look at what time you got up.
0:18:52 > 0:18:56- Elin, you got up - at between 7.15am and 7.50.
0:18:58 > 0:19:02- Lowri, you got up - at between 8.05am and 8.40am.
0:19:02 > 0:19:05- You got up at similar times.
0:19:06 > 0:19:10- Lowri, on average you get - just under nine hours' sleep...
0:19:11 > 0:19:13- ..and the expert says - that's adequate.
0:19:13 > 0:19:16- Elin, you get - less than eight hours' sleep.
0:19:17 > 0:19:18- Are you tired by the weekend?
0:19:18 > 0:19:20- Are you tired by the weekend?- - Yes.
0:19:21 > 0:19:23- Do you sleep more on the weekend?
0:19:23 > 0:19:24- Do you sleep more on the weekend?- - Yes, but it depends.
0:19:25 > 0:19:29- I don't have to get up early - in the morning, so I do sleep in.
0:19:30 > 0:19:31- I get up much later.
0:19:33 > 0:19:38- Experts say you should stick to - a routine when it comes to bedtime.
0:19:38 > 0:19:42- You should go to bed around 9.30pm - and get up at 7am.
0:19:42 > 0:19:44- What do you think of that?
0:19:44 > 0:19:45- What do you think of that?- - I don't know.
0:19:45 > 0:19:50- I think seven o'clock is too early - to get up on the weekend.
0:19:50 > 0:19:51- Yes.
0:19:53 > 0:19:56- The girls' sleep patterns varied.
0:19:57 > 0:20:01- On average, over the five days, - Elin got less sleep than Lowri...
0:20:01 > 0:20:04- ..even though - Lowri went to bed later.
0:20:04 > 0:20:06- We all have a body clock...
0:20:06 > 0:20:11- ..which allows us to sleep at night - and be awake during the day.
0:20:12 > 0:20:17- As darkness falls, the brain churns - out a hormone called melatonin.
0:20:17 > 0:20:20- As melatonin levels rise, - we become sleepy.
0:20:20 > 0:20:25- This hormone is released later in - the day in teenagers than in adults.
0:20:26 > 0:20:30- This leads to a two to three-hour - shift in the sleep pattern...
0:20:30 > 0:20:33- ..so we get less sleep - during our adolescence.
0:20:34 > 0:20:38- This can have a huge impact on - everyday life, especially at school.
0:20:39 > 0:20:43- It's thought that 35% of teenagers - are sleep deprived.
0:20:43 > 0:20:48- You can have short lapses - into sleep, called microsleeps.
0:20:48 > 0:20:50- As short as three or four seconds.
0:20:50 > 0:20:55- You're not with it and you're not - absorbing what's going on.
0:20:55 > 0:20:59- It affects your learning - and your academic achievement.
0:21:00 > 0:21:02- Lowri, you kept a sleep diary.
0:21:03 > 0:21:05- What time - did you say you went to sleep?
0:21:06 > 0:21:10- I'm sure I said - I went to bed at around 11pm.
0:21:10 > 0:21:14- You didn't fall asleep - until around midnight.
0:21:14 > 0:21:18- Were you checking - Facebook and Twitter on your phone?
0:21:19 > 0:21:21- Yes, maybe for about half an hour.
0:21:21 > 0:21:23- I just couldn't sleep.
0:21:26 > 0:21:29- Research shows that - devices like phones...
0:21:30 > 0:21:33- ..affect the time it takes us - to fall asleep.
0:21:33 > 0:21:36- If I'm on my phone - for a while at bedtime...
0:21:36 > 0:21:38- ..it does affect my sleep...
0:21:39 > 0:21:42- ..and what time I fall asleep.
0:21:45 > 0:21:48- Devices like tablets and phones - emit blue light.
0:21:48 > 0:21:53- This light may trick the body clock - into thinking it's still light.
0:21:54 > 0:21:58- This affects our melatonin levels - and makes us feel more awake...
0:21:58 > 0:22:00- ..and not ready to sleep.
0:22:01 > 0:22:05- The result is the body clock - is set back later and later.
0:22:06 > 0:22:09- Would you like - the school day to start later?
0:22:09 > 0:22:13- I wouldn't want it to start too late - or you'd come home late...
0:22:14 > 0:22:18- ..and you'd still have to - do your homework and do some sport.
0:22:19 > 0:22:21- You've seen your sleep data.
0:22:21 > 0:22:26- Will you change the time you go - to bed and the time you go to sleep?
0:22:27 > 0:22:32- I'll go to bed around nine o'clock - and get up around seven o'clock.
0:22:33 > 0:22:36- Sleep is essential for teenagers...
0:22:37 > 0:22:40- ..as their bodies and brains - are still developing.
0:22:40 > 0:22:43- The amount of sleep - we need varies...
0:22:43 > 0:22:47- ..but our sleep pattern changes - during adolescence...
0:22:47 > 0:22:49- ..keeping us awake longer.
0:22:50 > 0:22:53- This pattern will change again - as we mature...
0:22:54 > 0:22:58- ..but an hour or two more sleep - does teenagers a power of good.
0:23:00 > 0:23:05- Teenagers change dramatically, - both mentally and physically...
0:23:06 > 0:23:09- ..as they go - from childhood to adulthood.
0:23:09 > 0:23:14- As we mature, the physical - transformation is obvious...
0:23:15 > 0:23:17- ..but our brain also changes...
0:23:18 > 0:23:22- ..as it restructures and speeds up, - ready for adult life.
0:23:23 > 0:23:26- We learn to control - emotions and feelings...
0:23:26 > 0:23:29- ..and get through - alien social situations.
0:23:30 > 0:23:33- We yearn for independence - but we need guidance...
0:23:34 > 0:23:38- ..during these - exciting, confusing times.
0:23:38 > 0:23:42- Next time, we count bones - and take a look at the brain...
0:23:42 > 0:23:44- ..as we focus on an adult's life.
0:23:58 > 0:24:00- S4C subtitles by Eirlys A Jones
0:24:00 > 0:24:00- .