Vince Davidson, from Coldstream in the Borders, only emerged from the windowless, 10ft by 10ft shed earlier this year.
The 49-year-old fought with the King’s Own Scottish Borderers (KOSB) to eject Saddam Hussein’s forces from Kuwait.
But Mr Davidson was so badly affected by his experiences he moved out of the family home he shared with his wife and two children in 1999.
The garden shed was his home - a place he called his protective “bubble” - until January this year.
Apart from occasionally sleeping and washing in the family home, Mr Davidson lived as a recluse in the shed, taking meals and occasionally receiving friends there.
He said it was only when his daughter introduced him to Facebook that he began to reconnect with the world and he moved back into the family home in January.
Mr Davidson believes he is one of thousands of victims of Gulf War Syndrome, a condition blamed on the cocktail of drugs given to many soldiers at the start of the war.
He has decided to reveal the “embarrassment” of his 15 years living in a shed to highlight the plight of Gulf War Syndrome victims.
He said: “The shed was like my bubble.
“Everybody dealt with the symptoms in different ways. My way, unfortunately, was being in the shed in darkness.
“Basically I spent all my time in there. I was still dying inside with Gulf War syndrome,” he said.
“My wife would bring food. I would literally sit in the shed for weeks and listen to music.
“It was 10ft by 10ft with a couple of benches and no windows.”
Mr Davidson said in the years immediately after the war he suffered from insomnia, anxiety, memory loss and aggressive behaviour.
But it was the deaths of fellow veterans that hit him particularly hard and drove him to take refuge in the shed eight years after coming home.
“Attending friends’ funerals I started thinking, is it going to be me next?” he said.
After his family persuaded him to use Facebook at the turn of the year, Mr Davidson emerged from his shed within weeks.
“I realised there were lots of us in the same place,” he said. “A lot of them have the illness I have. It was a relief to be honest - I sort of felt a bit more normal.”
The former recluse founded the Facebook page Veterans Helping Veterans for the South East of Scotland.
He is campaigning to get Gulf War Syndrome officially recognised by the MoD.
“Still witnessing some veterans sitting on one seat at a window staring out - it’s sad to see in this day an age,” he said.
“That’s why I started Veterans Helping Veterans.”
Paying tribute to his wife of 28 years, Fiona, and daughters Mhari and Leah, he said: “I wouldn’t have be here without my family. I’d have been long gone.
“I’ve lost a lot of friends from the Gulf and Northern Ireland though illness and suicide.
“I used to be very bitter and hate the regiment and hate everything. But the hatred is a waste of time. I spend my energy on good things now.”