Retinal light perception and biological rhythms: The role of light in sleep and mood from an ophthalmic perspective (Review).
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing mechanistic and clinical literature without systematic search methodology
PubMed 41170746 · doi:10.3892/mmr.2025.13726
What was done
This narrative review synthesized evidence from animal models and human studies to evaluate the retinal mechanisms underlying circadian rhythm regulation. It focused on intrinsically photosensitive retinal ganglion cells (ipRGCs), melanopsin-mediated non-visual photic pathways to the suprachiasmatic nucleus (SCN), downstream nitric oxide-cyclic GMP signaling, and how ocular diseases (e.g., glaucoma, retinal degenerations) or artificial light exposure alter sleep and mood.
What was found
The abstract reports no quantitative data, sample sizes, or numerical effect sizes. It qualitatively describes that short-wavelength blue light stimulation of ipRGCs drives SCN synchronization, melatonin regulation, and affective state, and that disrupted photic input from ocular pathology or nighttime light exposure contributes to circadian misalignment and related sleep and depressive disorders.
Why it matters
It frames the retina as a key mediator of systemic circadian homeostasis, highlighting how ophthalmic pathology and spectral light management directly influence neuropsychiatric and sleep outcomes.
Limits
The paper is a narrative review without systematic search protocols, quality grading, or meta-analytic data pooling. The abstract provides no primary human trial data or quantitative effect estimates.