If the results of the at-home actigraphy show that you are still able to take part in this study, you will continue the final part of the screening procedure which is an inpatient visit to conduct a sleep study. The following tests/procedures will be done for this final screening visit: We will ask you to come into the sleep laboratory to sleep overnight (sleep study). A technician will attach the leads (wires) to your body and you will need to keep these leads on during the night. The attached wires will be connected to a machine to measure chest and abdominal (stomach area) movements, airflow at your mouth and lips, blood oxygen level, muscle tone, eye movements, heart rate and electrical activity of the brain. In the morning, the technician will remove the attached wires.