Perinatal light imprinting of circadian clocks and systems (PLICCS): A signature of photoperiod around birth on circadian system stability and association with cancer

Abstract

Recent findings from animal models suggest that plasticity of human circadian clocks and systems may be differentially affected by different paradigms of perinatal photoperiod exposure to the detriment of health in later life, including cancer development. Focusing on the example of cancer, we carry out a series of systematic literature reviews concerning perinatal light imprinting of circadian clocks and systems (PLICCS) in animal models, and concerning the risk of cancer development with the primary determinants of the perinatal photoperiod, namely season of birth or latitude of birth. The results from these systematic reviews provide supporting evidence of the PLICCS and cancer rationale and highlight that investigations of PLICCS in humans are warranted. Overall, we discuss findings from experimental research and insights from epidemiological studies. Considerations as to how to "test" PLICCS in epidemiological studies and as to the potential for non-invasive preventative measures during perinatal periods close our synthesis. If the PLICCS rationale holds true, it opens the exciting prospect for amenable, early-life, preventative measures against cancer development (and other disorders) in later life. Indeed, non-invasive anthropogenic light exposure may have enormous potential to alleviate the public health and economic burden of circadian-related diseases.

Birth seasonality of childhood central nervous system tumors: Analysis of primary data from 16 Southern‐Eastern European population‐based registries

“…Indeed, individuallevel data on potential effect modifiers not available in the present dataset, such as latitude, exposure to sunlight, type of outdoor activities, climatic changes and variations in seasonal infections, would be targets of future research to allow assessment of their potential role in CNS tumors risk, as shown in other childhood cancers. [55][56][57][58] Our results are derived from a large population-based collection of incident cases, which allowed sound analyses. In particular, two distinct analytic approaches were used, namely seasonal analyses by birth month using two statistical tests (Cuzick-Edward's and Walter-Elwood), as well as Poisson regression and meta-analyses by season of birth.…”

Exercise time cues (zeitgebers) for human circadian systems can foster health and improve performance: a systematic review

“…Moreover, within any given zeitgeber multiplicity, entrainment is determined by both external intensity and internal susceptibility 2. Determinants of the strength of zeitgebers include intensity, duration, phase timing and periodic frequency while the susceptibility of the receiving organism to such information can be assessed by the phase of internal time (indicating a phase response curve),23 and potentially by circadian system robustness 24. In effect, multiple zeitgebers such as light, noise, meals or social contacts may act synergistically or antagonistically, that is, they interact in terms of their ‘push’ or ‘pull’ on circadian rhythm phase 2.…”

Studying birth month and mortality: what about the perinatal photoperiod?

“…Photoperiod is the predominant time cue for circadian clocks that regulate myriad physiological processes, including blood pressure and fate of nutrients—processes that can affect cardiovascular disease. Importantly, perinatal photoperiods might imprint developing circadian systems and affect later life physiology 2…”

“…Such studies would complement similar investigations under way using UK Biobank data 4. If differential risks associated with photoperiod were observed, further research could target the hypothesised circadian imprinting mechanism 2…”