During the interview, participants will be asked questions about their sleep, cardiac, and ICD history. Participants will then visit the University of Florida for a medical history and will be connected to machinery to monitor their sleep. Participants will return home to sleep while still connected to the machine and will return the machine to the University of Florida the next day. A third visit will consist of completing questionnaires and a computerized neurocognitive performance battery to assess several areas of cognitive functioning. Participants will then go home and with brief daily diaries to complete for two weeks while also wearing an actigraph (wristwatch-like device) that measures arm movements to detect sleep/wake during that time.