We will use a 275-channel Whole-head MEG System (CTF Systems 2001 Inc.). Patients will have a screening, non-SD and SD MEG-EEG after their degree of sleepiness is assessed using the Epworth, Stanford and Karnolinska sleepiness scales. Starting one day after the MEG-EEG, SD and non-SDMEG-EEG will be performed in random order within 14-21 days of each other. This will ensure an equal amount of sampling effect in SD and non-SD data sets. The MEG-EEG session will last 90 to 180 minutes. Patients may take a break after at least 10 minutes in a scanner. We will attempt to record a comparable amount of awake and sleep data. At least thirty minutes of artifact-free baseline, non-SD and SD MEG-EEG will be analyzed. For the purpose of blinding, each modality will be read independently by two readers, each of whom will be blinded to the relationship of the MEG-EEG data to sleep deprivation, results obtained by the other modality and subjective degree of sleepiness. Only interpretations of each modality agreed upon by both readers will be accepted. When there is no agreement, a third independent reader will resolve the disagreement.