Alcohol's interactions with circadian rhythms. A focus on body temperature

Abstract

The complex interaction between alcohol and the body's circadian rhythm has become a rapidly expanding area in chronopharmacology. This area has key implications for the field of alcohol research, because understanding alcohol's effects on the body's internal clock will aid scientists in designing medications and behavioral interventions for treating alcohol abuse and dependence. A number of studies provide evidence that alcohol sensitivity and preference vary with circadian timing. However, only a few studies support alcohol's ability to influence the circadian phase directly. This review focuses on studies examining how alcohol and the body's circadian rhythm interact, using body temperature as an index of circadian rhythm function. Though the research is limited, findings indicate that alcohol sensitivity and preference for drinking to indeed appear to vary with circadian timing and that alcohol may act directly on the central pacemaker to alter circadian functioning.

Figure 1

A representation of the field of chronopharmacology as it relates to alcohol.

Figure 2

Body temperature (T_b) can be significantly influenced by environmental or ambient temperature (T_a) in the presence of alcohol. Alcohol-induced disruption of normal thermoregulatory mechanisms results in hyperthermia or hypothermia in response to higher or lower T_a, respectively. A lower T_b appears to be protective of the system, because hypothermia causes the body to be less sensitive to the central depressant effects of alcohol. Initial sensitivity or tolerance to alcohol also may play a part in the overall behavioral effects. The circadian rhythm influences T_b or behavior (e.g., amount of activity) via an area of the brain involved in regulating bodily rhythms (i.e., the suprachiasmatic nucleus [SCN]).