Techniques for controlling therapy based on a physiological parameter indicative of ventricular filling pressure, such as various cardiovascular pressures, are described. One or more values of the physiological parameter that are collected during nighttime, or while the patient is otherwise asleep, inactive, or within a recumbent position, may be compared to one or more values of the physiological parameter collected during daytime, or while the patient is otherwise awake, active and/or upright. A therapy, such as for treating physiological factors that may lead to worsening HF, may be initiated or adjusted based on the comparison, e.g., if the nighttime values exceed the daytime values.
