B737 Next Generation Undifferentiated
Flight Crew Air Transport Pilot (ATP)
Flight Crew Type 5709
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Wake Vortex Encounter
Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance; Flight Crew Regained Aircraft Control; Flight Crew Requested ATC Assistance / Clarification
Environment - Non Weather Related; Procedure
Approaching DSNEE intersection; we encountered two significant wake events. Descending to the crossing altitude of 8000; with autopilot engaged; the aircraft banked sharply to the right. The autopilot went to CWS (Control Wheel Steering); and lateral guidance was lost. Regained control/composure with autopilot engaged; LNAV/VNAV level at 8000 when another wake encounter banked aircraft left greater than 35 degrees with significant buffeting.  Turned autopilot off and lost about 400 ft in the process of recovery.
On descent to 8000 on the arrival procedure; passing approximately 9500 MSL we experienced a semi-violent right roll due to wake turbulence from aircraft in front of us. The captain maintained aircraft control; but LNAV dropped off and the autopilot reverted to CWS (Control Wheel Steering). At approximately 8500 MSL we experienced another rapid roll to the left and a steep descent. The Captain disengaged the autopilot and corrected the bank (which was approaching 35-40 degrees) and began leveling off. I announced 'Altitude' as we passed 7800 MSL. He corrected the descent and began to climb back to 8000 MSL. The minimum altitude observed was 7650 MSL. I notified ATC of the wake turbulence and altitude deviation and requested a vector to exit the turbulence. The Controller immediately gave us a vector away from the preceding aircraft and a descent to 6300 MSL.
B737 flight crew reported encountering wake turbulence from the preceding aircraft on the DSNEE1 Arrival into SNA that resulted in rolls to the left and right as well as a loss of 400 ft in altitude.