1. Please avoid using words like ‘some’, ‘something’ and ‘thing’ in formal essays. They are too vague and make little contribution to the message of the text.
2. ‘And’ was used 13 times in this text. Two things: first of all, try to use synonyms for that, e.g. ‘as well as’, ‘and also’ and others. Secondly, avoid using two conjunctions in the same clause, like here: “… a rough time studying and working and lack of rest”
3. “I will/would like to outline this problem”
4. We need a comma here to introduce the same part of speech, in this case gerund: “They spend most of their time sitting, probably not paying attention”.
5. “The lack” is used twice, it could be easily replaced with the phrase “insufficient amount of” in this particular context to avoid word repetition.
6. You probably meant “social ties” here
7. Phrased like this, it feels like doctors should discuss that among themselves. I believe the idea was to establish a dialogue between pupils and doctors. If that is the case, then: “… doctors at schools should encourage pupils to talk about their health”
8. I would suggest phrases like ‘highlight’, “stress the importance of”.