She said Nicky Hilton left the jail "in hysterics."
"It's sad. It's like right out of the movies," Nicky Hilton told People. "The glass partition, the orange jumpsuit. Everything."
Kathy Hilton said she hoped some good could come of the experience.
"But the point is that I hope this will shine a light on everybody (in those jails). That's the positive," she said. The jails, she said, "need financial help, and it's very sad to see what's going on in there."
Paris Hilton was originally sentenced to 45 days in jail for violating her probation in a DUI case by driving without a license.