Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Distraction; Confusion; Fatigue
Deviation - Altitude Undershoot; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Flight Crew Returned To Clearance; Flight Crew Became Reoriented
Environment - Non Weather Related; Human Factors
Climbing out of MKE this afternoon; we broke out around 5;000 feet. When we broke out; we were looking right into the sun. I used my right arm to shield my eyes; but it was still difficult to see the instruments. The FO asked me if I wanted the autopilot; but I declined because I wanted to get the aircraft stabilized in the climb. I was decreasing the pitch to accelerate to 250kts. After I got the plane to 250kts; I was going to ask for autopliot to get my sun shade; but Departure called us then and cleared us up to 10;000 feet. I heard the clearance and kept climbing. When the FO was done reading back the clearance; I asked for autopilot on. He turned it on. Neither of us realized that the airplane had captured at 5000 feet; he hadn't set 10000 feet yet; and I hadn't asked for a vertical mode. He said; 'Autopilot on' and I turned to get my sun shade. I got it in place; looked down at my instruments and the FO said; 'We're descending.' We had been at probably around 6500 when he turned the autopilot on. When he said we were descending; I bumped the stab trim to disable the autopilot and got the plane climbing again. At that point; we realized we still had 5000 feet bugged and no vertical mode. We corrected those problems and re-engaged the autopilot and continued the flight.It's hard to pinpoint the root cause of the event because there were so many causes. We were both struggling to see in the glare of the sun in our eyes. We had task saturation because we were trying to fly the plane in that challenging situation while reading back and complying with a new clearance; and also trying to get the autopilot on. We were both tired. I made several minor mistakes that we caught right away after that on this flight. We were tired because almost every leg of this trip we had to fly an instrument approach past the final approach fix; and almost every leg had some kind of issue (MX; security; passenger deplaning; etc).Very simply; regardless of the flight conditions; after having the autopilot engaged; verify the aircraft flight path before turning away to take care of other items (like getting the sun shade).
CRJ-200 Captain reported an excursion from cleared altitude due to fatigue; distractions; and lack of autoflight mode awareness.