A Tangled Threesome: Circadian Rhythm, Body Temperature Variations, and the Immune System
Microbes Evolution Phylogénie et Infection, Institut Recherche et Développement, Aix-Marseille University, 13005 Marseille, France
Institut Hospitalo-Universitaire-Méditerranée Infection, Assistance Publique-Hôpitaux de Marseille, 13005 Marseille, France
Médecine Intensive-Réanimation, Hôpital Nord, Assistance Publique-Hôpitaux de Marseille, 13915 Marseille, France
Service d’Anesthésie et de Réanimation, Hôpital Nord, Assistance Publique-Hôpitaux de Marseille, 13915 Marseille, France
Authors to whom correspondence should be addressed.
Received: 29 December 2020
Revised: 6 January 2021
Accepted: 10 January 2021
Published: 18 January 2021
In mammals, including humans, the body temperature displays a circadian rhythm and is maintained within a narrow range to facilitate the optimal functioning of physiological processes. Body temperature increases during the daytime and decreases during the nighttime thus influencing the expression of the molecular clock and the clock-control genes such as immune genes. An increase in body temperature (daytime, or fever) also prepares the organism to fight aggression by promoting the activation, function, and delivery of immune cells. Many factors may affect body temperature level and rhythm, including environment, age, hormones, or treatment. The disruption of the body temperature is associated with many kinds of diseases and their severity, thus supporting the assumed association between body temperature rhythm and immune functions. Recent studies using complex analysis suggest that circadian rhythm may change in all aspects (level, period, amplitude) and may be predictive of good or poor outcomes. The monitoring of body temperature is an easy tool to predict outcomes and maybe guide future studies in chronotherapy.