ABC7 News learned the attack took place last night. The worker was punched and choked, but did not need to go to the hospital, according to the union representing psychiatric technicians.
The hospital kept Unit T-3 under lockdown until around 9:30 a.m. Sunday.
A union representative did not know if the patient had been arrested.
The attack comes after a patient killed a staff member last fall and numerous attacks on patients by other patients.
Patient Jess Massey was found guilty last week in the October 2010 murder of psychiatric technician Donna Gross.
Napa State Hospital houses many criminally-insane patients.