Credit: Everett Collection

Amanda Peterson, the actress known for starring in 1987’s Can’t Buy Me Love alongside Patrick Dempsey, passed away this Sunday in her sleep at the age of 43.

Her mother, Sylvia Peterson, tells PEOPLE that Amanda’s death came as a “very, very big surprise,” and recalls that in her daughter’s last moments, “she was in bed, and she’d had a wonderful day, and we were planning on a dinner the next day.”

Amanda—who her mother described as “a very, very cute person”—is survived by her second husband and two children. The cause of her death is still currently unknown, but Sylvia tells PEOPLE that she suspects that Amanda’s sleep apnea may have had something to do with it.

To read the rest of Peterson’s remarks, head over to PEOPLE.