These behaviours are -
1. Staying up late and struggle to get up in the morning.
2. Irritable mood
4. More connect with friends
5. Food dada
6. Laziness like their body is suddenly filled with lead.(they become Helium with phonecall from a friend)
7. General shabbiness of room and hygiene
9. Foul language.
All these "sins" are entirely overlooked if child scores obscene marks in exams. (Some other time later about these "brilliant" children)
(This is Indian way of asking question so usually it runs 5 min long. I compressed it here)
It happens in ALL human beings.
You should be seriously worried if it DOESN'T happen with your child by 16 or 18 years of age.
(In our beloved motherland "crucial years" of the child usually starts on day of parents marriage and ends with parents demise)
Difficulty is what parents expect from kids and how their worry drives them.
And explosions in small, closed space are devastating for humans.
Excessive friendliness usually backfires and no adolescents wants to be friends with a 45 year old unless it gives massive financial dividends.
Not sweating small change is HUGE. Brushing teeth, combing hair, cleaning up room, having "nutritious diet" all the time is all small change.
Concrete help in their struggles (where possible) really works.
A smile and a pat on the back goes a long way than a 20 min sermon "from the bottom of heart"
There are no "corrective" treatments for normal adolescent changes. They are to be welcomed with a smile, open arms and lots of deodorant.