They have identified a small (500 to 3000 daltons) naturally occurring bioactive substance (most likely a peptide as it is trypsin-sensitive) in the CSF of afflicted patients. Although this substance requires further identification of its chemical structure, it is currently referred to as a "somnogen" because it has been shown to cause hyper-reactivity of GABAA receptors, which leads to increased sedation or somnolence. In essence, it is as though these patients are chronically sedated with a benzodiazepine (medication which acts through the GABA system) such as Versed or Xanax, even though they do not take these medications.[22][23]