Esfandiari, a 67-year-old grandmother and academic with dual US-Iranian nationality, said today that she knew she had to be disciplined to survive in Iran's Evin prison.
''I decided that I was not going to fall apart. If I was going to avoid succumbing to despair I had to make the best of the conditions that were put at my disposal,'' said Esfandiari, who was detained on May 8 while visiting Tehran to see her mother.
She was released on August 21 on bail of 320,000 dollars and left Iran on September 2.
''To maintain my mental and physical well being I imposed a strict discipline on myself -- a daily schedule of exercise, reading and also writing projects I carried on in my head,'' she told reporters on her first day back at work.
Esfandiari, the director of the Middle East program at the Woodrow Wilson International Center for Scholars, said when she was not being interrogated she did stretching exercises on the floor, walked for 3-4 hours straight then broke for lunch before exercising for several more hours each afternoon.
By the end of her imprisonment she had lost weight, she said.
The evening was dedicated to reading. Esfandiari was able to borrow English-language books through the guards from fellow US-Iranian prisoner Kian Tajbakhsh. She had to cover her eyes to sleep because the lights in her room were on 24 hours a day.
Esfandiari said she forced herself not to think about her husband, daughter and two grandchildren because she did not want to get depressed.
Iran accused Esfandiari of involvement in a US-led plot to topple its clerical establishment in a ''soft revolution.'' Washington has dismissed the allegation.
Analysts have seen Esfandiari's detention and that of other US-Iranians as part of a broader crackdown on dissent when Tehran is under pressure over its nuclear program, which Washington sees as a bid to build bombs despite Iran's denials.
Esfandiari said she was never physically mistreated during nearly four months in prison but never really understood why she was arrested.
She was not allowed to leave the country and was questioned for four months before being detained. She was never told there would be charges against her.
She said she was mostly asked about the activities and programs of the Middle East program at the Wilson Center and that people in the ministry seemed to believe that think tanks and foundations were instruments to carry out a revolution.
''I tried to convince them that the Wilson Center is a transparent institution, so whatever we did is on our Web site,'' she said.
REUTERS TB RN0158