ClonidineAdrenergic alpha-AgonistsNight BlindnessNight CareAdrenergic alpha-2 Receptor AgonistsYohimbinePreanesthetic MedicationReceptors, Adrenergic, alpha-2SympatholyticsAdrenergic alpha-AntagonistsImidazoline ReceptorsCircadian RhythmReceptors, Adrenergic, alphaGuanfacineInjections, SpinalAnalgesicsSleepWork Schedule ToleranceAdjuvants, AnesthesiaIdazoxanAdrenergic alpha-2 Receptor AntagonistsOxymetazolineNorepinephrineBlood PressureHeart RatePrazosinSleep DeprivationDouble-Blind MethodPremedicationPhentolamineAnalgesia, EpiduralReceptors, AdrenergicHypnotics and SedativesSleep StagesDioxanesNight TerrorsMorphineWakefulnessPolysomnographyMelatoninDose-Response Relationship, DrugGuanabenzAnesthetics, LocalHemodynamicsPain, PostoperativeNaloxoneNeostigmineSympathetic Nervous SystemTime FactorsDexmedetomidineEpinephrineMedetomidineDrug InteractionsArousalMethoxamineMethyldopaBupivacaineDesipramineInjections, EpiduralAntihypertensive Agents