DISTRIBUTED LEAD FUNCTIONALITY TESTING

Techniques for performing lead functionality tests, e.g., lead impedance tests, for implantable electrical leads are described. In some of the described embodiments, an implantable medical device determines whether a patient is in a target activity state, e.g., an activity state in which lead impedance testing will be unobtrusive, such as when a patient is asleep, or capture information of particular interest, such as when the patient is active, in a particular posture, or changing postures. The implantable medical device performs the lead functionality test based on this determination. Additionally, in some embodiments, the implantable medical device may group a plurality of measurements for a single lead functionality test into a plurality of sessions, and perform the measurement sessions interleaved with delivery of therapeutic stimulation.