Sixty miles west of the Somali border, in Dadaab, Kenya, is the largest refugee settlement in the world. First built a quarter century ago, more than 300,000 Somali refugees now live in a dusty, sprawling community of makeshift houses and tents originally intended for 90,000. Children have been born in the Dadaab refugee camps—and the children of those children, too. Waves of Somali people first fled to Dadaab because of a civil war that is still ongoing. In the past decade, more came still because of famine and drought that killed hundreds of thousands of people.

To live in Dadaab, they have escaped violence and death—only to plunge into an abyss of uncertainty. In 2014, the United Nations’ refugee agency, the UN High Commissioner for Refugees, resettled less than 1 percent of all Somali refugees in Kenya, two-thirds of whom reside in Dadaab. Overcrowding in the camps means that they don’t have enough bathrooms or sufficient security. Sexual assault is a looming threat for women and children. Not to mention their makeshift homes are not really theirs: Last April, Kenya’s government threatened to shut down the Dadaab camps and deport the refugees.

“They are not certain of the future,” says Michael Kamau, a psychotherapist who works with Dadaab refugees through the international nonprofit Center for Victims of Torture. “They are under a lot of stress.”

The stress from this instability—in addition to the trauma they’ve already experienced—means that refugees are particularly vulnerable to mental disorders. Refugees resettled in Western countries might be as much as ten times as likely to have PTSD; one in three refugees has PTSD or depression. (In American adults, it’s more like one in 14.)

As you’d imagine, all that can make it tough for refugees to piece together new lives in new countries. “You’re suddenly in a new environment. You don’t have a social support system, and you have to figure out how to live and how to support your family,” says Liyam Eloul, a CVT psychotherapist working in Jordan, where over 900,000 Syrian refugees live. “Often, people who are suffering from PTSD, increased anxiety, or depression are less able to manage these situations.”

It doesn’t just hinder the refugees in the short-term, either: Mental disorders have long-term consequences for physical health. People with PTSD are twice as likely to have heart disease, for example. “You’re constantly feeling fight or flight. Your heart rate is higher; your level of adrenaline production is higher; your consumption of blood sugar goes up, and this causes a lot of these physical disorders in the long run,” Eloul says.

Groups like UNHCR and CVT offer services to treat refugee mental disorders, but as the population of displaced people grows, these resources are dwindling. At the end of 2014, almost 60 million people—one in every 122 humans—were refugees, asylum seekers, or internally displaced persons. Between 2013 and 2014, the number of refugees increased by 16 percent, but UNHCR’s 2014 funds, which largely come from government donations worldwide, increased barely 13 percent. “You want to get as far as you can with every client you work with, but the reality is that it’s just not possible,” Eloul says. “There’s always this pressure in the back of your mind that if one person gets a continuation of sessions, that means another client gets a delay.”

Not every refugee needs the intense level of care that Eloul provides—some just need guidance toward community social groups, or a friendly football game. But experts don’t fully understand how effective these different support systems are. “We still don’t have a good understanding of these psychological mechanisms,” says Angela Nickerson, a psychologist who researches refugee mental health at the University of New South Wales in Australia. “Why do some people adapt, and some don’t? What psychological interventions work best? We need more evidence-based research to guide these services.”

The lack of research is partly because humanitarian agencies didn’t pay much attention to mental health until about fifteen years ago. Furthermore, even though the vast majority of refugees live in low-income countries, most research focuses on refugees resettled in developed countries where studies are easier to conduct. “We need good research in low-income countries,” says Peter Ventevogel, UNHCR’s mental health specialist. “The whole context is different.” For example, the entire country of Chad, which hosts 450,000 refugees, has only one psychiatrist. Research based on western-style psychiatric care wouldn’t translate over to their system.

The oldest refugee camp in Dadaab turns 25 this year. Kamau helps people there manage their stress; he works to keep them socializing. He encourages refugees to quit chewing khat, a leaf that has stimulating, mildly addictive properties. But the fact is, the main occupations there are waiting and worrying. “The majority are just idle,” Kamau says. “There’s no place to work. They don’t have anything else to do.” The arid climate means that farming is nearly impossible. A small minority of Dadaab refugees do work as nurses or teachers or act as aides for humanitarian agencies, but the routine of a typical male refugee in Dadaab, says Kamau, might involve chatting with some neighbors, and then waiting for UNHCR food shipments to come. Women are slightly more occupied, taking care of children and fetching water.

The children who were born in Dadaab have never known any other life. “They were born here; they grew up here; they went to school here, and now some of them are looking for employment,” Kamau says. “It is unfortunate that there are no jobs for them. They have a lot of energy, but there’s no place for their energy.” That might not be anything even the best mental health caregiver can fix.