NEW HAVEN, Conn. — A Connecticut prisoner who said he was forced to sleep on a mattress that smelled of mildew and missing much of its stuffing was awarded $12,000 Friday by a jury that concluded he suffered cruel and unusual punishment.

Harold Bell, who is serving a 12-year prison sentence for first-degree assault, suffered joint pain, headaches and chronic sleep deprivation because of the mattress, said his attorney, Antonio Ponvert III.

“No reasonable person would allow this mattress into their home,” Ponvert said. “No one would let their dog sleep on it. No one would sleep on it themselves for an hour, let alone one night, let alone 200 nights, which is what he was forced to do.”

Ponvert said it took about seven months for the prison to replace the mattress, which he called “putrid” and “foul smelling.” Bell’s injuries were substantiated by prison medical staff, he said.

The verdict, handed up by a federal jury in Hartford, is a rare victory for a prisoner, Ponvert said.

“I am extremely pleased and thankful that the jury understood what Mr. Bell had gone through and perhaps more importantly understood the significance of enforcing an important amendment of the Bill of Rights, despite what I’m sure was intense pressure not to do that,” Ponvert said, noting the unpopularity of prisoners.

Jaclyn Falkowski, a spokeswoman for Attorney General George Jepsen, said she respects the jury’s work and says an appeal is unlikely.

It wasn’t clear why the prison didn’t replace the mattress sooner, Ponvert said. A prison official testified he didn’t recall the case, he said.

Andrius Banevicius, a Department of Correction spokesman, said officials couldn’t comment before reviewing the decision.

The jury found Bell had proven his right to be free from cruel and unusual punishment was violated, awarding him $5,000 for the violation and $7,000 for his injuries.

Bell, 38, said the mattress had been slashed into and slit down the middle, and its condition forced him to lay curled up in a fetal position. Bell began seeking a new mattress at MacDougall-Walker Correctional Institution in Suffield in June 2008 and a warden ordered he get a new one in September 2008, but he didn’t get a replacement until January 2009, Ponvert said.

Bell represented himself for much of the case, Ponvert said.

“I think this will assist Mr. Bell when he gets out in being able to hold his head up a little higher and live back in society with some pride,” Ponvert said. “I think he felt probably for the first time in more than a decade that a group of ordinary citizens have seen him like a human being.”