Greens senator Scott Ludlam has announced he will be taking leave from his parliamentary duties to deal with long-term mental health issues.
The WA senator, a co-deputy leader of the minor party, revealed his decision on Friday, saying he would return "as soon as I'm able to give the commitment the work demands".
"I am taking a leave of absence to treat depression and anxiety. These are issues I've been dealing with for a while," he wrote on Facebook.
"The team in my office will continue to support and work for the constituents of WA, and work with my Senate colleagues to manage my portfolio responsibilities."
Senator Ludlam will be offered a "pair" in the Senate - by which a single vote is sacrificed on the opposing side of debates to cancel out his absence - as long as is required.
The senator is active on social media and has been particularly outspoken on issues of online privacy and national security legislation. His portfolios include communications, international aid, defence, foreign affairs and nuclear technology.
He initially lost his seat at the 2013 election but emerged victorious when Western Australians were forced to go back to the polls again because ballot papers were lost in a recount.
Shortly before the WA special election, he gave a speech on the stereotyping of the state he represents, arguing that the "mining state" moniker was insulting and simplistic. He was addressing a near-empty Senate but the speech went viral online.
Senator Ludlam emerged as one of two co-deputy leaders when Richard Di Natale took over the leadership of the party in mid-2015 after the surprise resignation of Christine Milne.
Senator Di Natale wished his colleague a speedy recovery on Friday afternoon. "We love you Scott," he tweeted.
WA Labor leader Mark McGowan said "all WA parliamentarians wish you the very best".
"A brave thing to do today."
There have been several high profile cases of mental illness in Australian politics. Former trade minister Andrew Robb took leave in 2009 to deal with depression and has become a well-known mental health advocate.
A large number of MPs have talked privately of marriage breakdown, alcoholism, isolation and the stress of scandals. Former MP Mal Washer, a GP whom many politicians consulted, estimates that 20 per cent are on anti-depressants.
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