A strong support network is critical after being released from detention, an expert says.

With her prison ordeal over, Brittney Griner will now face the challenge of transitioning back into life at home — where a strong support network will be critical, a mental health expert said Friday.

“Most people’s trajectory isn’t the one that you kind of see in films, where you’re this damaged person years later — you’re never the same,” said Neil Greenberg, a clinical psychiatrist and professor of mental health at King’s College London. “Most people manage to reintegrate into whatever their new life will be.”

Ms. Griner, who had been detained in Russia for 10 months, landed early Friday in San Antonio and is expected to go to a local Army medical center where she will be examined and receive any necessary medical treatment.

Prof. Greenberg has worked on about two dozen cases involving detained people and hostages, including advising the British government on the repatriation of kidnapped individuals. He stressed that every case and detention experience is different.

While he is not involved in Ms. Griner’s case and was not familiar with it specifically, he said in the short term most people experience emotional swings after their release from detention and can expect “trauma-like symptoms” such as poor sleep and irritability. Those are signs of distress, not illness, in most cases, said Prof. Greenberg, who is also the director of the British mental health consultancy March on Stress.

Jason Rezaian, the former bureau chief for The Washington Post in Tehran who was imprisoned in Iran for 18 months, recounted the early days after his release in 2016 in an episode of his podcast “544 Days.”

“Fear and anxiety were just the first layers,” he said of the trauma he and his wife experienced. “We started misplacing things, little things like keys or a wallet.”

Support from friends, family and colleagues or teammates is typically a bigger factor than counseling and therapy in determining long-term mental health for formerly detained people, Prof. Greenberg said. “The evidence we have says that people like us, the professionals, should be there to support the process. We shouldn’t be getting involved early on,” unless the person becomes unwell, he said.

He said supporting those around the formerly detained person — like ensuring that Ms. Griner’s wife, Cherelle Griner knows that it is normal for her spouse to experience distress in the coming weeks — is important, too.

“The role for experts is to make sure that you prepare the ground effectively for someone coming back into a supportive environment,” he said.

If people have support and are able to return to their normal routines and reconnect socially, their detention eventually can become part of their past and a story to “tell around the campfire,” he said.

After the predictability of detention, including meal times and exercise restrictions, recently released people can struggle with readjusting to having to make decisions and handling day-to-day difficulties, Prof. Greenberg said. But over time, those feelings settle, he added.