title: Biphasic effects of alcohol as a function of circadian phase.
abstract: OBJECTIVE
  To assess how alcohol affects multiple sleep latency tests (MSLT) and subjective measures of stimulation/sedation when alcohol is given at different circadian phases.
  
  
  METHODS
  Twenty-seven healthy young adults (age 21-26 yr) were studied.
  
  
  METHODS
  Double-blind placebo and alcohol (vodka tonic targeting 0.05 g% concentration) beverages were each administered three times during the 20-h forced desynchrony protocol. Sleep latency tests and Biphasic Effects of Alcohol Scale (BAES) were administered on each forced desynchrony day. The outcome variables for this study include sleep onset latency (SOL) and stimulation and sedation value (from the BAES). Each outcome variable was associated with the ascending or descending limb of the breath alcohol concentration (BrAC) curve and assigned a circadian phase within a 90° bin.
  
  
  RESULTS
  BrAC confirmed targeted maximal levels. Only outcome variables associated with the ascending and descending limb of the alcohol curve were analyzed for this article. Alcohol administered at a circadian time associated with greatest sleepiness showed longer SOL compared with placebo when measured on the ascending limb of the BrAC curve. We also found longer SOL with alcohol on the ascending limb of the BrAC curve in a circadian bin that favors greatest alertness. We observed shorter SOLs on the descending limb of the BrAC curve, but with no circadian phase interaction. The subjective data were partially consistent with the objective data.
  
  
  CONCLUSIONS
  The physiologic findings in this study support the biphasic stimulating and sedating properties of alcohol, but limit the effect to specific circadian times.
authors.affiliation: Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI, USA. Eliza_van_Reen@brown.edu
authors.forename: Eliza
authors.initials: E
authors.lastname: Van Reen
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Rupp
authors.forename: Christine
authors.initials: C
authors.lastname: Acebo
authors.forename: Ronald
authors.initials: R
authors.lastname: Seifer
authors.forename: Mary A
authors.initials: MA
authors.lastname: Carskadon
mesh_terms: D000328:Adult; D000434:Alcoholic Beverages; D000704:Analysis of Variance; D001944:Breath Tests / Q000379:methods; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D002940:Circadian Rhythm / Q000502:physiology*; D004311:Double-Blind Method; D004562:Electrocardiography / Q000187:drug effects / Q000379:methods; D004569:Electroencephalography / Q000187:drug effects / Q000379:methods; D004576:Electromyography / Q000187:drug effects / Q000379:methods; D000431:Ethanol / Q000378:metabolism / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography / Q000187:drug effects / Q000379:methods; D012890:Sleep / Q000187:drug effects*; D012894:Sleep Stages / Q000187:drug effects; D055815:Young Adult
chemical_list: D002492:Central Nervous System Depressants; D000431:Ethanol