AceShowbiz - Lindsay Lohan is so terrified about her upcoming three-month prison sentence, she's struggling to sleep, according to the actress' mum Dina. The "Mean Girls" star is due to head behind bars on July 20 after breaking the terms of her probation from a previous DUI arrest by failing to attend court-ordered alcohol education classes.

Lohan was seen sobbing in the courtroom after the judge delivered the sentence on Tuesday, July 6, and her mum admits the 24 year old has been restless ever since because she's "scared to death" about going to jail. Dina tells Entertainment Tonight, "She's strong, but until someone faces something as devastating as that (jail)... we're going to have to see... Lindsay's scared to death. It's very difficult, we're not sleeping well, we're not functioning. We cry a lot and we hug a lot. She's petrified, we all are. We're angry. We're disappointed in the system."

And Dina is hopeful a new attorney will help her daughter file a successful appeal before her prison term, adding: "(Lindsay's) a fighter, and until the final result we're not giving up. I think it's time we get another attorney just to see it from another light and do damage control." The lawyer who defended Lohan in her probation violation resigned on Thursday, July 8 and the star will now reportedly be represented by Tiffany Feder-Cohen.