Le coût métabolique, physiologique et comportemental de la resynchronisation de l'horloge biologique sur les cycles naturels.

Curriculum vitae Here

Post-Doctoral Position :  Université de Neufchatel, Suisse

Sleep is a key component in each species’ behavioural repertoire, likely to have played a major role in human cognitive evolution. Sleep patterns vary hugely between and within species, resulting in a multitude of sleep strategies. Surprisingly, however, the mechanisms and function of sleep has remained subject to much debate, and some very basic questions remain unanswered: Are there within-species differences in sleep strategies and how much is it due to social factors? What are the consequences of sleep variation for cognitive performance, social success and biological fitness? These and related questions lack empirical investigation and theoretical framing, especially in natural conditions and in species phylogenetically close to humans, thus overlooking a crucial part of our own evolutionary history. Focusing on a wild population of chimpanzees (Pan troglodytes) in Budongo forest (Uganda), this project aims to investigate inter-individual variation in sleep strategies, their endogenous and social drivers, and their consequences on fitness and cognition. So far, we know from a very limited number of species that sleep strategies may vary drastically between individuals, but the fitness consequences of these strategies have been very rarely addressed. Indeed, the majority of studies on sleep have been conducted in the laboratory, missing the ecological and evolutionary aspects of a core biological function. I will collect direct behavior observations, camera trap video data, thermal imaging as well as simple cognitive tests data. Recording night-time sleeping behavior in wild chimpanzees and relating it to daytime performance and life-time fitness represents a new and exciting challenge in extending our knowledge about the origins of human sleep and cognition, by determining how evolution has shaped sleep strategies in our closest cousins.

Budongo conservation field station


  • Hozer C, Pifferi F. (2021) Relationships between endogenous circadian period, physiological and cognitive parameters and sex in aged gray mouse lemurs (Microcebus murinus). Chronobiology International
  • Tournissac M, Vrabic N, Vu T-M, Hozer C, Tremblay C, Planel E, Pifferi F, Calon F. (2021) A beta3-adrenergic receptor agonist reverses memory deficits and reduces insoluble Aβ42/Aβ40 ratio in a mouse model of Alzheimer’s disease.
  • Alzheimer's Research & Therapy 13:103
  • Hozer C, Perret M, Pavard S, Pifferi F. (2020) Survival is reduced when endogenous period deviates from 24 h in a non-human primate, supporting the circadian resonance theory. Scientific Reports 10:18002
  • Hozer C, Pifferi F. (2020) Physiological and cognitive consequences of a daily 26h photoperiod in a primate: exploring the underlying mechanisms of the circadian resonance theory. Proceedings of the Royal Society B 287: 20201079
  • Hozer C, Aujard F, Pifferi F, Perret M. (2019) The Biological Clock in Gray Mouse Lemur: Adaptive, Evolutionary and Aging Considerations in an Emerging Non-human Primate Model. Frontiers in Physiology (10)1-13