Summary
This research demonstrates that circadian rhythms control daily fluctuations in blood leukocyte numbers through inflammatory cytokines and microbial signals, with immune cell counts peaking at specific times of day. For lighting designers and healthcare professionals, this suggests that circadian-aligned lighting environments may have downstream effects on immune function and inflammatory responses beyond sleep and alertness.
Key Findings
- Serum transferred from donors at specific times of day caused increased leukocyte numbers in recipient circulation, indicating time-of-day-dependent circadian factors in blood
- Pharmacological blocking of inflammatory cytokines suppressed the time-dependent leukocyte oscillations, identifying cytokines as key circadian mediators
- Germ-free mice showed lower leukocyte counts and reduced circadian oscillations in blood cellularity, implicating the microbiome in circadian immune regulation
Categories
Sleep & Circadian Health: Demonstrates that circadian rhythms regulate oscillatory leukocyte counts in the bloodstream, linking light-dark cycles to immune cell mobilization timing.
The Science of Light: Provides mechanistic insight into how circadian timing influences downstream physiological processes, relevant to understanding light's systemic biological effects.
Author(s)
SM Hergenhan
Publication Year
2020
Related Publications
Sleep & Circadian Health
- Phototransduction by retinal ganglion cells that set the circadian clock
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- The twoâprocess model of sleep regulation: a reappraisal
- Melanopsin is required for non-image-forming photic responses in blind mice
- Strange vision: ganglion cells as circadian photoreceptors
The Science of Light
- Phototransduction by retinal ganglion cells that set the circadian clock
- Color appearance models
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Melanopsin is required for non-image-forming photic responses in blind mice