Sadfishing is when someone posts about an emotional problem in an attempt to attract attention, sympathy or hook an audience.
The phenomenon has been driven by celebrities who have been accused of posting exaggerated claims about their emotional problems to generate sympathy and draw people onto their sites.
The new study, by Digital Awareness UK (DAUK) found that young people with genuine mental health issues who legitimately seek support online are nevertheless facing unfair and distressing criticism that they are jumping onto the same publicity bandwagon.
In some cases, this rejection can damage their already fragile self-esteem and even result in them becoming more vulnerable to sexual ‘grooming’ online.
The study, commissioned by the Headmasters' and Headmistresses' Conference (HMC) is based on face-to-face interviews with more than 50,000 children aged 11 to 16. The report argues that students can be left feeling disappointed at not getting the support they desire and it can subsequently make their emotional or mental health problems worse.
Earlier this year a separate, Organisation for Economic Co-operation and Development (OECD) study, of 250,000 teachers in 48 countries, suggested schools in England had the highest incidence of problems with online behaviour.
It indicated 27% of head teachers in England had to deal with problems related to online bullying every week - compared with an international average of 3%.