By Richard Allen Greene
Nearly 2,000 US troops have been killed in Iraq since the 2003 invasion, and tens of thousands wounded. But many have found themselves dealing with psychological - as well as physical - trauma. In the second of a five-part series, BBC News talks to soldiers with post-traumatic stress disorder (PTSD) and related symptoms.
Steve MacMaster can't sleep without medication: "If people knew what I was thinking, they would not want to associate with me," he says.
Aaron Jones does not feel comfortable without a gun around: "I lived in Iraq for almost a year with a gun on me all the time or right next to my bed."
Kathy's boyfriend - who did not want to be named - had to stop watching the news: "When he sees people going to Iraq, or coming home, he can get really upset.
"Whatever you say, he'll find something in it to disagree with. So we don't watch the news."
All three veterans of the US occupation of Iraq are having nightmares about what they saw and did there - and they are among tens of thousands of US troops suffering from psychological trauma after coming home.
Death on the road
Sgt MacMaster, 42, is haunted by his memories of commanding a transport unit.
He was in charge of 40 soldiers driving fuel tankers between Nasiriya and Baghdad - a day-long trip that "was like a bunch of safe forts with no-man's-land in the middle and everybody taking potshots at you".
A soldier under Sgt MacMaster's command fell asleep at the wheel
For the safety of his own troops, he had been ordered not to stop moving.
"At the beginning of the war I was told: 'Don't stop for anybody - if they get in the way, run them over.'"
And he had not been in the country long before he saw a lorry run over a little girl in the road begging for food.
"I had seen dead Iraqis before, but they were fighters. These were people who were getting hit in an innocent way."
He also saw soldiers under his command suffer horrific injuries.
One fell asleep driving a fully loaded 16,000kg (35,000lb) fuel truck. It crashed and rolled over, but the driver survived.
"Her face had been smashed in. I couldn't get communications to my helicopters so I decided to take this girl in my humvee and blitzed up to Baghdad as fast as possible."
The stress of the mission started getting to him.
"I couldn't sleep or eat. I had butterflies in my stomach attacking me."
Sgt MacMaster's superior noticed the change and sent him to a psychologist, who sent him on to a military hospital where he was diagnosed with PTSD and depression.
A lot of Iraq veterans are hearing that diagnosis these days.
A study at the US Army's Walter Reed hospital in Washington, DC, found that up to 17% of Iraq veterans - about one in six - suffered depression, anxiety or PTSD.
About 425,000 US troops have served in Iraq since the invasion in March 2003, meaning some 70,000 could be experiencing psychological trauma.
Some early indicators are worrying.
The divorce rate among US army officers has tripled in the past three years.
The National Coalition for Homeless Veterans says that in 2004 its affiliates helped 67 veterans of Iraq or Afghanistan - only a year or two into those conflicts.
That set off alarm bells at the charity, since experts say it took traumatised Vietnam veterans an average 12-15 years to end up in shelters.
"Homeless service providers are deeply concerned about the inevitable rising tide of combat veterans who will soon be requesting their support," the coalition warned.
The number of veterans coming home from Iraq, it added, "is unlike anything the nation has experienced since the end of the Vietnam war".
Vet Centers - community outreach counselling centres set up by the US Department of Veterans' Affairs - have seen nearly 19,000 Iraq or Afghanistan veterans to date, says Dr Al Batres, the head of the VA's readjustment counselling service.
'Intrusive and disturbing'
Tim Beebe, regional director of the New England Vet Centers, says the numbers are increasing month by month.
And his counsellors say they see the same symptoms over and over again: Sleeplessness, anger, irritability, anxiety, depression.
PTSD rarely goes away on its own, Tim Beebe warns
"PTSD can be intrusive - you can be out with your family and suddenly you're thinking about an event in Iraq. It becomes disturbing to the veteran, difficult to understand," Mr Beebe says.
"It's not something the veteran can will away or adapt to. And it can be chronic and lifelong if not treated."
But - although pre- and post-deployment mental health screening is becoming standard in the US military - many veterans do not seek treatment.
Some simply have no professional services nearby.
Aaron Jones says many veterans think they can simply "suck it up and drive on", as the military has taught them to do.
Kathy's boyfriend - a 14-year Army veteran who did two tours in Iraq and has known friends who were killed there since he came home - is one of them, she says.
It is the unseen injuries that are worrying the Pentagon
He doesn't even talk to his veteran friends about his experiences, she says.
"He told me they have a rule that they don't talk about it - they go out to have fun, and if they talk about Iraq, they don't have fun," she says.
"I'm the only one he talks to. I've heard the same miserable stories time and again and I don't know what to say. He doesn't want to be consoled."
Even some of those who have had help continue to struggle with trauma.
Steve MacMaster would like to stop taking medication for his condition but fears the consequences.
"I don't want to go back to the way I was in Iraq, where I became reckless and thought the only way to end it was to take a bullet - and started hoping for the bullet."
On Wednesday, BBC News investigates the Iraqi experience.