A medical device detects a patient posture state and adjusts therapy based on the detected posture state. A patient posture state may be transient. To avoid adjusting therapy in response to transient posture states, a dwell time may be imposed. Using the dwell time, only those posture states that are assumed by a patient for a minimum length of time will result in therapy adjustment. To help ensure that the dwell time is set to an appropriate length of time, patient therapy adjustment data may be analyzed. Therapy adjustments made during the dwell time may indicate that the dwell time is too long. Therapy adjustments made prior to the initiation of the dwell time may also indicate that the dwell time is too long. Therapy adjustments made by the patient after expiration of the dwell time may indicate that the dwell time is too short. Based on analysis of the therapy adjustment data, the dwell time can be adjusted to a length that is appropriate for the patient and/or posture state.