If the first screening visit shows that you are able to continue to take part in this study, you will continue the screening part of the study at home. The following will be done at home: We will ask you to undergo an at-home actigraphy and keep a daily sleep diary for two weeks to document your sleeping habits. For the actigraphy you will be asked to wear a small wrist-watch like device. This device will monitor and record your motion, and will also test your sleep and wake periods. It may be worn for up to 2 weeks, 24 hours per day (except while taking a shower).