Students awaiting A-level examination results are turning to drink to relieve the stress, according to a report.
A University of Hertfordshire report found one in 10 parents believe their stressed-out children drink more.
The teenagers suffer anxiety, disturbed sleep, mood swings and loss of self-esteem between the exams and their grades, the research found.
The whole family is affected with 25% of mothers and 16% of fathers admitting stress ahead of the exam results.
Mood swings by their teenage children was regarded as a telling factor.
One in 10 parents said it was evidence that their child's alcohol consumption was increasing while 4% claimed their children were smoking more in the run-up to results day.
YouGov surveyed 1,570 British parents online in July for the University of Hertfordshire which said the key is for parents and teenagers to talk things through.
A spokesman said: "There are always alternatives, even if students don't get the exact results they need."