Summary
This review explains how the master circadian clock in the SCN, entrained by light-dark cycles, coordinates melatonin and cortisol rhythms that in turn regulate the HPA axis and immune system function. For lighting designers and healthcare practitioners, it underscores that disrupting light-dark cycles can dysregulate not only sleep but also endocrine and immune health, reinforcing the importance of circadian-supportive lighting environments.
Key Findings
- The SCN master clock synchronizes body rhythms to the external light-dark cycle and drives hierarchical peripheral oscillators governing neurological, endocrinological, and immunological functions.
- Melatonin and cortisol are identified as the primary circadian-regulated hormones linking light exposure patterns to HPA axis activity and immune modulation.
- Seasonal changes in light exposure produce marked alterations in the endocrine system, HPA axis, and immune system parameters, highlighting the physiological importance of consistent circadian light entrainment.
Categories
Sleep & Circadian Health: Reviews the role of the SCN master clock, melatonin, and cortisol in regulating circadian rhythms synchronized to light-dark cycles.
The Science of Light: Discusses how light-dark cycle entrainment of the SCN drives downstream hormonal and immune responses through circadian clock genes and proteins.
Author(s)
Z Şahin, ÖF KALKAN, O AKTAS, A KALKAN
Publication Year
2023
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 two‐process 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