Clinical Research Directory

Inclusion Criteria: * Those receiving primary total knee arthroplasty (TKA) * 80 years or less, age 18 or greater Exclusion Criteria: * History of cardiovascular bundle branch block * Actively taking selecrtive serotoin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors (MAOIs), or having treatment via counseling/psychotherapy for major depression or anxiety, bipolar, or psychotic disorder * Pre-operative narcotics (defined as more than 1 prescription in the past 3 months) * Self-reported use of alcohol in excess of \>2 drinks/day (in men) and \> 1 drink/day (in women) * Use of prescription sleep aids (e.g., Ambien, Trazadone) prior to surgery (i.e., melatonin or other OTC sleep aids are permitted) * History of major sleep disorder (e.g., obstructive sleep apnea (OSA), restless leg syndrome, narcolepsy) * Pregnant, breastfeeding or planning to become pregnant in the next 3 months post-surgery. No pregnancy testing will be performed; screening will rely solely on participant self-report. * Unable to take the study medication(s) due to contraindications with other medications the patient uses * Have been diagnosed with (or are at risk of) narrow-angle or angle-closure glaucoma. In order to be eligible, participants must be able to report that they have had their eyes dilated within the past year without problems. * Have severe urinary retention or difficulty emptying your bladder. * Had glaucoma-related eye procedures (e.g., laser iridotomy) * Ongoing use of glaucoma eye drops.