Circadian changes in psychologic effects of ethanol

Area of Science:

• Pharmacology
• Human Physiology
• Psychology

Background:

• Circadian rhythms influence physiological and psychological responses.
• Ethanol's effects can vary based on the time of day it is consumed.
• Understanding these variations is crucial for safety and performance assessments.

Purpose of the Study:

• To investigate the impact of ethanol ingestion timing on psychologic and physiological variables in healthy males.
• To determine if ethanol's effects are dependent on the time of day.
• To correlate observed effects with pharmacokinetic data.

Main Methods:

• Six healthy males (22-26 years) participated in a controlled study.
• Ethanol (0.67 g/kg) was administered at four different times (0700, 1100, 1900, 2300 hours) in a randomized order.
• Psychologic (self-rated inebriety, vigor) and performance (reaction time, eye-hand coordination) tests were conducted over 24-36 hours.

Main Results:

• Self-rated inebriety and performance decrements (speed, eye-hand skill) were most pronounced when ethanol was ingested at 2300 hours.
• Effects on physical vigor, tempo, grip strength, and blood pressure were not time-dependent.
• Oral temperature changes showed time-dependent effects but were not linked to pharmacokinetics.

Conclusions:

• The timing of ethanol ingestion significantly impacts subjective intoxication and cognitive/motor performance.
• Circadian variations influence ethanol's central nervous system effects more than peripheral ones.
• Further research is needed to elucidate the mechanisms behind time-dependent ethanol effects.