title: Sleep and circadian rhythms: do sleep centers talk back to the clock?
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D001933:Brain Stem / Q000166:cytology / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D005246:Feedback / Q000502:physiology; D006801:Humans; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000502:physiology*