Sleep Actigraphy in Postural Tachycardia Syndrome (POTS)

We propose to use actigraphy (measured by activity watches) as a tool to quantify sleep disturbances in patients with orthostatic intolerance compared with healthy control subjects. In this pilot study, we will test the null hypothesis (Ho) that there are no differences in the sleep quality between patients with orthostatic intolerance and healthy control subjects.

Inclusion Criteria: * Diagnosed with orthostatic intolerance by the Vanderbilt Autonomic Dysfunction Center * Control subjects will be free of orthostatic intolerance and other major medical problems, free of medications during the study * Age between 18-65 years * Male and female subjects are eligible. * Able and willing to provide informed consent Exclusion Criteria: * Overt cause for postural tachycardia (such as acute dehydration) * Self-report of pregnancy * Inability to give, or withdrawal of, informed consent * Other factors which in the investigator's opinion would prevent the subject from completing the protocol