Relative light sensitivities of four retinal hemi-fields for suppressing the synthesis of melatonin at night

Abstract

The magnitude of the stimulus to the biological clock will depend upon the distribution of circadian phototransduction circuits across the retinae and the spatial distribution of luminous stimuli in the environment. The present study compared nocturnal melatonin suppression for light exposures to the superior, inferior, nasal, and temporal retina in one eye independent of shading from the brow and the nose. The stimulus was a 40° diameter luminous disc, half of which was blue light (LED, λ peak = 470 nm) and the other amber light (LED, λ peak = 590 nm). Experimentally, the orientation of the bipartite disc was rotated to each of the four cardinal points of the visual field. A full, 40° blue disc was also employed by replacing the amber half-disc with another blue half-disc. The blue full- and half-discs always produced 100 photopic lx at the cornea. As hypothesized, nocturnal melatonin suppression was statistically greatest when the blue half-disc was delivered to the nasal hemi-field (35%); the other three hemi-fields were equally affected by the blue half-disc (≈20%). Melatonin suppression for the full-disc was 24%, which was not statistically different than the average suppression for the four hemi-fields of 27%.

Measurement of Circadian Effectiveness in Lighting for Office Applications

“…Much of the evidence on how light affects the human circadian system relates to studies dealing with nocturnal melatonin suppression and phase resetting [22,28,. In two seminal studies, Brainard et al [40] and Thapan et al [41] exposed pupil-dilated human subjects to different monochromatic stimuli in the late evening hours and measured their resulting melatonin levels after 90 min (Brainard et al) and 30 min (Thapan et al) of light exposure using blood samples.…”

“…On the contrary, Smith et al [27], who examined nocturnal melatonin suppression in older adults (>60 years) after 2 h of light exposure to 1000 lx, reported no significant differences for an upper versus middle visual field stimulation. In a recently published study, Rea et al [28] systematically investigated the relative light sensitivities of the four retinal hemi-fields (i.e., nasal, temporal, superior, and inferior) in terms of suppressing nocturnal melatonin secretion after 1 h of corresponding blue light exposure (λ max = 470 nm, 100 lx at the cornea, monocular vision). In accordance with the conclusions drawn by Visser et al [22] and Rüger et al [23], they found that the nasal part of the human retina produced an approximately 15% greater response to circadianeffective light exposure than any of the other three retinal hemi-fields, where basically no significant differences occurred between temporal, superior, and inferior stimulation.…”

Verification, analytical validation and clinical validation (V3) of wearable dosimeters and light loggers

“…Importantly, the physiological effect of light varies with the region of the illuminated retina. [88][89][90][91][92][93] At present, spatially resolved measurements are not generally available for wearable dosimetry to incorporate these effects.…”

Functional connectivity of brain networks with three monochromatic wavelengths: a pilot study using resting-state functional magnetic resonance imaging

“…In the visual system, one study found increased activation in posterior and occipital regions using red-light stimulation in esotropia and blue light in exotropia 21 . Interestingly, other authors found that melatonin suppression by blue (470 nm) and amber (590 nm) light exposure is hemispherically dependent in the retina, observing more melatonin suppression in the nasal hemifield 22 .…”