I'm surprised that the actors didn't age significantly during filming through the constant depressing characters that they had to portray!
Although 'Skins' drew on teenage stereotypes, drug taking, rebelling against work and parents and tackled everyday issues such as teenage pregnancy, sexuality, dysfunctional families and mental disorders I believe the fourth series pushed these to the extreme and it became slightly unrealistic and made for a depressing watch.
The characters had already been fully established in the third series and one gets the feeling that the writers were pulling at strings for the fourth, knowing that they had reached the end of the line. Effy Stonem, known for being quiet and offering statements such as "Sometimes I think I was born backwards...I hear words go past me backwards. The people I should love, I hate, and the people I hate..." deteriorates into psychotic depression. She attempts suicide, rather ironically is manipulated by her psychiatrist, and loses the man she finally admitted to loving. The story line is farfetched and one is left questioning why it all had to end on such a downer?
There was not one point at which I wanted to laugh, compared to the first and second series where Chris and Anwar were constant humour inducers. The first two series and possibly the third managed to keep you counting down the days till the next episode but this wasn't the case for the fourth series which became tedious to watch and almost an effort to tune into.