Manning testified Thursday that he was forced to sleep naked the previous night because of his attempt to show an officer that he wasn't a danger to himself. Manning said that he told the officer that he could have used the waistband of his underwear or his flip-flops to hurt himself but hadn't done so.
That night, Manning testified, his underwear, flip-flops and glasses were removed from his cell.
His lawyers hope the judge will at least take his experiences during confinement into account and sharply reduce his sentence should he be convicted at his court-martial, which is expected to begin early next year.
The defense has said it plans to have Manning plead guilty to lesser offenses and fight other charges as being too extreme.
The hearing is scheduled to resume this weekend, with prosecutors expected to argue that the detention conditions were warranted. The Pentagon has maintained that Manning was held in accordance with rules governing all maximum-custody detainees at Quantico.
Counts against Manning include aiding the enemy, wrongfully causing intelligence to be published on the Internet, transmitting national defense information and theft of public property or records.
If he's convicted on all counts, he could face a life sentence.