A heartbroken mother has revealed how her son went from an outgoing teenager with a passion for art and music to a zombie addicted to synthetic marijuana sleeping on the streets of Melbourne in a matter of months.

Brisbane mother Leanne Thompson fondly described her son Daniel, 25, as ‘six-foot-four, with broad shoulders, a good looking face and an amazing sense of humour.’

Graduating from a prestigious Catholic school in Victoria and completing a TAFE certificate in horticulture, land conservation and land management, the ‘exceptionally strong-willed’ man quickly found full-time work in landscaping.

But one trip to the notorious Rainbow Serpent music festival in 2014 – an event marred by countless drug arrests and overdose deaths in recent years – triggered a downward spiral that ended with drug addiction and homelessness.

Now Ms Thompson flies interstate to Melbourne once every week, 1,400 kilometres each way, to stand guard over her estranged son through the night, reminding him he is still loved and welcome back home.

Daniel Thompson, 25, has been living on the streets of Melbourne since March. His mother has revealed her heartbreak watching her son's life deteriorate after developing an addiction to synthetic marijuana

Brisbane mother Leanne Thompson said she flew to Melbourne each week to visit her son Daniel, 25, (pictured left) and stand watch through the night

Ms Thompson said Daniel had graduated from a prestigious Catholic school and left behind a full-time landscaping job to move to Melbourne last year (pictured with sister at a wedding in 2015, just two years ago)

Ms Thompson (pictured)  is calling on the state government to introduce involuntary rehab to save her son

Ms Thompson (pictured)  is calling on the state government to introduce involuntary rehab to save her son