The pilot reported that he was returning to his home airport in dark night conditions. He performed a low approach, about 50 feet above the runway, to clear it of any wildlife that may have been present. After turning crosswind, he turned off the landing lights due to a high ambient glare that left him with a partial loss of night vision for a few seconds. He also stated that he neglected to set the elevator trim to maximum up, and that he had maintained a full cruise power setting. He reported that the altimeter was dark and not readable after he turned onto downwind. Shortly after turning onto the downwind, the airplane unexpectedly contacted the ground, which resulted in structural damage to both wings and the fuselage. The airplane came to rest in an upright position in a nose down attitude. The downwind portion of the traffic pattern is on a gradual slope that is about 200 feet higher than the runway. The pilot reported that he had made numerous night landings to his home airport. On the accident landing he did not cross-check the altimeter during the approach, and had not properly configured the airplane for landing. He added that if he would have followed his normal regimen, and configured the airplane properly, the airplane would have been about 1,000 feet higher than it was when it impacted the terrain. The pilot reported that there were no mechanical problems with the airframe or engine at the time of the accident.