Hocter said the long period of solitary confinement hurt Manning's physical and mental health, making him more irritable and anxious, and less cooperative.
One of the security measures was the removal of Manning's underwear at night, starting March 2, 2011, after he told a guard that if he wanted to kill himself, he could hang himself with the waistband. Coombs suggested Manning was commenting on the absurdity of his situation.
Coombs produced an email in which Quantico's chief legal officer at the time, Lt. Col. Christopher Greer, made light of the underwear episode with a Dr. Seuss parody: "I can wear them in a box. I can wear them with a fox. I can wear them in the day. I can wear them so I say. But I can't wear them at night. My comments gave the staff a fright," Coombs read.
Oltman acknowledged that he responded to the email with the signature, "Sam I am," another Dr. Seuss reference.
"Was it funny to you that Pfc. Manning was being stripped at night?" Coombs asked.
"No, it was not, it was a very serious issue," Oltman said.
At least a dozen supporters of the 24-year-old Army private attended the second day of what is expected to be a six-day hearing.
Manning faces possible life imprisonment if convicted of aiding the enemy, the most serious of the 22 charges that he faces.
He is accused of sending hundreds of thousands of classified Iraq and Afghanistan war logs and more than 250,000 diplomatic cables to WikiLeaks while he was working as an intelligence analyst in Baghdad in 2009 and 2010.
The materials Manning is suspected of leaking include sensitive reports on foreign governments and leaders and a 2007 video clip of a U.S. helicopter crew gunning down 11 men later found to have included a Reuters news photographer and his driver. The video garnered worldwide attention. The Pentagon concluded the troops acted appropriately during the attack, having mistaken the camera equipment for weapons.