After being embroiled in weeks of online aggression on Twitter, in which her well-documented battles with depression were raised, about 2am yesterday Dawson posted: ''Hope this ends the misery'' and ''You win x''. Police and ambulance were called to Ms Dawson's Darlinghurst apartment at 3.05am yesterday.

The incident followed hours of online abuse, in which scores of Twitter users ramped up an online campaign against Ms Dawson, calling for her to kill herself and sending pornographic images and graphic photos of bloodied corpses to her account.

Ms Dawson was later admitted to hospital. A spokesman said she was expected to make a full recovery.

While Dawson has been a regular combatant on Twitter and has not shied away from commenting on controversial subjects, it appears the stakes were raised considerably in the past 48 hours with the Anonymous group highlighting her Twitter account and activating its members to target her from around the world.

In recent weeks, Dawson has been the victim of repetitive bullying on Twitter. She had taken to re-tweeting the abuse she suffered at the hands of strangers.

She told Fairfax on Tuesday: ''I always bite back, I know it's my problem but I can't just let it go without having something to say.''

The case has outraged Twitter users, who have called for compassion in social media.

Mamamia website publisher Mia Freedman wrote: ''There needs to be a way for abusive trolls on Twitter to be held accountable for their harassment. It'd be illegal to do that in person''.

The presenter of 7.30 on the ABC, Leigh Sales, wrote: ''I'm appalled at people's cruelty''.

People who abuse others on Twitter could fall foul of the Commonwealth Crimes Act, which prohibits using ''a carriage service to menace, harass or cause offence or for the purposes of a threat''.

The University of Canberra senior lecturer in journalism and communications, Jason Wilson, said people could be motivated to post anonymous abuse at strangers for a range of motivations including attention and notoriety. ''The anonymity makes it a lot easier to kind of confront a stranger with that sort of abuse.''

He said women, celebrities and social media newcomers were more likely to suffer vitriolic abuse online. ''The question for me is, how do we respond to it? Not so much why do people do it, that's a matter for psychologists and psychiatrists.

''My recommendation is, to the extent you can, ignore it [abuse] and see it as more of a system fault rather than it being about you.''

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