Visit 3 (approximately six weeks after you begin treatment for your sleep disorder): If you have used the device that is being used to treat your sleep disorder enough, you will be invited to come for visit 3. All of the tests performed during the first visit will be performed again during visit 3. Thus, you will need to follow the same instructions about food, medicine, and exercise as described under visit 1 before coming to visit 3. You will again have a fingerstick blood sugar level performed. In addition, about 2 tablespoons of blood will be drawn. This blood and a random urine sample will be stored (frozen) in case possible risk factors of reduced heart rate variability are discovered in the future and in case these factors need to be examined before and after treatment for a sleep disorder. The same questions asked with regard to the likelihood of you falling asleep in various situations will be asked. This visit will last approximately 1-1 ½ hours.