EMB 135 First Officer reported Cabin Pressure problems during cruise. With 20 minutes of flight left; hypoxia symptoms were noted by both Pilots. The Flight Crew donned oxygen masks immediately and monitored Cabin Pressure through to landing at destination airport.

Narrative

It began when we started our descent into ZZZ; our auto pressurization system showed a decrease and then an increase and our ears began popping this was abnormal. We monitored and the pressurization began to stabilize however in the descent the cabin pressure remained higher than what it does regularly all the way to the ground. Other than that we had no issues on the first leg. When on the ground in ZZZ; Person A talked to Maintenance and explained what had happened and Maintenance said that if the pressurization system corrected itself then we are okay to continue. We also saw that there was a write up earlier in the day from the crew that had the plane before us; they were having pressurization EICAS messages occur when starting Engine 1. Maintenance had taken a look and the pressurization system operated normally when they checked it. Before taking off from ZZZ; Person A and I briefed that we were going to request a lower altitude in case we had another pressurization anomaly. After taking off in ZZZ we got an annunciation that the baggage door had opened and our auto pressurization was not working correctly as well; we did not lose any pressure so we continued and followed the QRH procedure. In manual mode we were able to get the pressurization exactly where it needed to be for the altitude we were at based on the graph in the QRH so we continued the flight per the QRH procedure. We also requested a lower altitude in case we ran into any other pressurization anomalies ATC was able to accommodate and Person A made sure to be very clear that we were not requesting priority handling. As we were flying to ZZZ1 we continued to monitor the cabin pressure and QRH graph and made very small adjustments to keep it exactly where it was supposed to be. When they had about 20 minutes left of flying and were getting to the arrival portion of the flight I began to feel a little bit euphoric as well as a little bit of tingling in my fingers. I immediately told Person A what I was feeling they said they felt off as well and said to put on our masks immediately. We both are aware of the signs of hypoxia and how it can creep up on people without them even realizing it. Once our masks were on we continued to monitor cabin pressure and nothing had changed which was contradictory to what we experienced. We did not want to take any chances with hypoxia so we requested a lower altitude and let ATC know it was because we were having pressurization issues but made sure to confirm we were not requesting priority handling. At this point we were on the arrival and ATC was giving us lower while on the arrival we were task saturated making sure we had complied all necessary checklist and we got up to 265 kts. at 8000 ft. Person A immediately corrected and the rest of the arrival and approach went smoothly. Something is not operating correctly with the pressurization system of the aircraft. Maintenance finding the issue with the pressurization system and fixing it.