Sleep comes quickly after 10 hours on the water. And that makes a difference to Bart Lindberg.
Lindberg, from Brainerd, ran hundreds of missions in dozens of countries during his time as a watercraft operator in the Army. When Lindberg came home in January, he couldn't sleep.
"I had to drink if I wanted to sleep," he said.
On July 22 he and three other veterans threw their canoes in the Mississippi headwaters and started paddling for the Gulf of Mexico. Ever since then Lindberg has been sleeping just fine.
The trip is an outgrowth of the Warrior Hike, started by Iraq War veteran Sean Gobin in 2012 to help fellow soldiers recover from post-traumatic stress disorder (PTSD).
The Warrior Hike challenges veterans to cover 2,000 miles of the Appalachian Trail. Gobin said the aim is to help soldiers literally 'walk off the war' but he realized many veterans are not physically able to walk so far over rough ground.
Lindberg's Mississippi River trip is a test case to see if paddling is strenuous enough to bring the same sort of mental relief veterans reported after the Warrior Hike, but something a soldier might be able to do even with physical injuries.
Recently the group landed on the banks of the Mississippi near the small town of Deer River in northern Minnesota for a night's rest and blueberry pancakes fried up by the landowner.
"Mark is outpacing me," Lindberg said over coffee, "and he served in Vietnam."
At 63, Mark Fox is the oldest guy on the trip. He's also the most physically fit, hiking 600 miles of the Appalachian Trail before getting on the Mississippi.
"It was literally a walk in the park," he said.
Fox said he didn't see much combat during his deployment. Gobin recruited him for the water rescue skills he accumulated over years on the Eagan Fire Department.
The other paddlers said they are still working through the scars of war.
Annie Balthazar, of Fayetteville, West Virginia served as a military anesthetist in Iraq. She saw dozens of children critically injured by makeshift bombs -- bleeding soldiers still gripping their rifles on their way into surgery. When Balthazar got back, she said her personality had changed.
"PTSD manifests differently in different people," she said.
Balthazar's PTSD, she said manifested in a total lack of patience. She couldn't handle small problems, or delays.
Lindberg described the symptoms he's felt since his military discharge. Nightmares flood his mind with memories of the times his finger was on the trigger, ready to pull. He still hears voices. Before getting on the Mississippi, he silenced them with alcohol.
"I think I'm doing better now," he said.
"Yeah," Fox said, "You're doing better."
After a few weeks on the water, Lindberg thinks paddling is helping him. Balthazar feels a bit more forgiving of delays. In a few months, they'll have a clinical measurement of the Mississippi's effect on their brains.
The paddlers group are being studied by a team of researchers led by Georgia Southern University psychology professor Shauna Joye. She screened each paddler for symptoms of PTSD, anxiety and depression before setting off. After 2000 miles, she'll screen them again.
It's early in the trip yet, but Joye is optimistic about the results. She's been studying Warrior Hikes for a few years, using in-person interviews and industry standard psychological surveys.
The last group of hikers she followed saw huge improvements in mental health.
"All but one person went from clinically diagnosed with PTSD," she said, "to a point where they would not be diagnosed with PTSD."
So far, follow up interviews suggest these veterans are retaining improvements from the wilderness, Joye said.
The studies have admittedly small sample sizes, just a handful of hikers at a time, but Joye said hiking or paddling may appeal to many veterans as a part of their treatment--and to those reluctant to seek help.
The Veterans Affairs department treats PTSD in many different ways, but Joye said all of them involve a lot of time talking to "shrinks." As a veteran herself, she said recognizes why that can be a barrier.
"In the military, getting treatment feels like weakness," she said. "A lot of people just don't go."
No one looks at hiking or paddling a few thousand miles as a sign of weakness, and that allows veterans like Lindberg to buy into the experience.
The paddlers plan to reach The Gulf of Mexico by late November; the "Abby and The Vets" blog is tracking their progress.