Rising numbers of young people are seeking help for worries about exam stress, according to ChildLine.
Figures show that the charity conducted 3,077 counselling sessions about the issue in the last year - up 9% on 2014/15.
In addition, youngsters took part in 1,127 counselling sessions about exam results - up 20% on 2014/15.
About a quarter of these meetings took place in August, when teenagers are awaiting GCSE and A-level results, the NSPCC-run helpline said.
One 15-year-old boy told counsellors: "All I can think about is exams and I can't deal with it any more.
"I revise all night because I'm so worried I'll fail and I feel so tired all the time. I can't really concentrate on other things and I'm not really eating properly either. These exams are only my mocks, and I don't know what I will be like for the real exams if I can't even deal with the mocks."
And a 17-year-old girl admitted: "I feel so overwhelmed at the moment so it's impossible to concentrate on revising. I'm worried that I won't get the grade I am predicted now.
"I don't know where to start and I think I am too far behind now to catch up. I'm worried that people will say I am attention-seeking if I tell them how I feel."
NSPCC chief executive Peter Wanless said: "The exam period can be a very stressful and anxious time for young people.
"As these figures reveal, the pressure to do well is being felt by an increasing number of young people across the country. We hear from lots of young people each year who are anxious, worried or panicking about their exams and revision. We want to let them know that they are not alone and that ChildLine is here to listen to them."
The helpline has launched a new video for children and young people giving tips and advice on coping with exams.
These including suggesting that youngsters should take regular breaks from revising, do some exercise, get a good night's sleep and try to think positively.
Separate advice for parents and carers says that they should not place unnecessary pressure on children to achieve certain grades and help them to revise by leaving them time and space to do so.
Youngsters can call ChildLine free on 0800 11 11.