B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Total 3400
Physiological - Other; Situational Awareness; Time Pressure; Troubleshooting; Workload
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Illness / Injury
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Diverted; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Aircraft
Delayed departure due to aircraft being towed over from a maintenance hangar. Departure from RWY 26L at ZZZ and flew SID with approved deviations to avoid buildups to the Northwest. At approximately [time] EDT; just after leveling off at 33K' and NNE of ZZZZZ; CABIN ALTITUDE warning light came on with audible horn and cabin altitude climbing through 10K'. We donned oxygen masks; established communications; and Captain pulled out the QRC to run the Cabin Altitude Warning checklist. As the cabin altitude continued to rise past towards 12K'; we [notified] ATC (ZZZ Center) and initiated a descent to 10K' and continued with QRC procedures. During descent we turned west toward the shoreline; asked for current/forecast weather conditions and decided to divert to ZZZ1. Captain continued to run the emergency checklist referencing the QRH from the iPad. After cabin altitude was indicating below 10K' we took oxygen masks off. After approximately 5-10 minutes with the masks off; I felt some 'hypoxia like' symptoms and told the Captain I needed to go back on the oxygen. We both donned the masks again until descending through 6K' at which point the symptoms previously experienced had gone away. Captain was in communications with the cabin throughout the event and we both acknowledged and sent messages to the company via ACARS. Both the approach and landing on RWY 17L at ZZZ1 were uneventful and as briefed.
B737-800 First Officer reported a loss of pressurization at altitude and resulting emergency descent. Pilot reported possible hypoxia.