Validation of Circadian Biomarkers in Patients With Sleep Disorders

Current methods for assessing circadian timing require sampling over hours (or even up to a day) while the patient is in controlled conditions. The investigators aim to develop a method that can estimate individual circadian time with a single blood sample taken at any time of the day or night. To do this, the investigators will use two state of the art methods, a plasma proteomics-based method to identify a panel of rhythmic proteins (extending our preliminary data) and a whole blood-derived monocyte-based method using a panel of 15 transcripts (to validate and extend a recent study). We will test both methods in a series of patients with circadian rhythm sleep disorders. We will validate separately the proteomics-based biomarker and the monocyte-based transcript biomarker, and also explore whether combining them can improve the accuracy of our timing estimates. In all cases, circadian phase estimates from the biomarker panels will be compared with those derived from plasma or saliva melatonin (the current "gold-standard" circadian phase marker).