Melanopsin, photosensitive ganglion cells, and seasonal affective disorder

Abstract

ROECKLEIN, K.A., WONG, P.M., MILLER, M.A., DONOFRY, S.D., KAMARCK, M.L., BRAINARD, G.C. Melanopsin, Photosensitive Ganglion Cells, and Seasonal Affective Disorder…NEUROSCI BIOBEHAV REV x(x) XXX-XXX, 2012. In two recent reports, melanopsin gene variations were associated with seasonal affective disorder (SAD), and in changes in the timing of sleep and activity in healthy individuals. New studies have deepened our understanding of the retinohypothalamic tract, which translates environmental light received by the retina into neural signals sent to a set of nonvisual nuclei in the brain that are responsible for functions other than sight including circadian, neuroendocrine and neurobehavioral regulation. Because this pathway mediates seasonal changes in physiology, behavior, and mood, individual variations in the pathway may explain why approximately 1–2% of the North American population develops mood disorders with a seasonal pattern (i.e., Major Depressive and Bipolar Disorders with a seasonal pattern, also known as seasonal affective disorder/SAD). Components of depression including mood changes, sleep patterns, appetite, and cognitive performance can be affected by the biological and behavioral responses to light. Specifically, variations in the gene sequence for the retinal photopigment, melanopsin, may be responsible for significant increased risk for mood disorders with a seasonal pattern, and may do so by leading to changes in activity and sleep timing in winter. The retinal sensitivity of SAD is hypothesized to be decreased compared to controls, and that further decrements in winter light levels may combine to trigger depression in winter. Here we outline steps for new research to address the possible role of melanopsin in seasonal affective disorder including chromatic pupillometry designed to measure the sensitivity of melanopsin containing retinal ganglion cells.

The Relationship between a Night Usage of Mobile Phone and Sleep Habit and the Circadian Typology of Japanese Students Aged 18 - 30 yrs

“…The over use of their smart phone especially in night time would make their circadian typology evening typed through the exposure to lights from the display of the phone (including the light with 460 nm length which is main wave length for absorption of melanopsin as a key light sensor to control circadian clock phase and also plasma melatonin concentration of humans: Roecklein et al, 2013) or a psychological effects. The over use of the phone would be avoided for promoting the mental health and sleep health of Japanese students aged 18 -30 years.…”

Possible contributions of skin pigmentation and vitamin D in a polyfactorial model of seasonal affective disorder

“…Seasonal affective disorder possesses a complex etiology that involves several causal and contributory mechanisms [13,19]. Vitamin D is a phylogenetically old steroid hormone whose presence researchers have documented in at least 36 tissues and 900 genes as of this writing.…”

“…Consistently, researchers have observed lower levels of vitamin D in persons with progressively darker skin as well as lower seasonal variability of vitamin D. Therefore, corresponding darkly pigmented irises should lead to diminished nonvisual light input. This pattern of relationships suggests that persons with greater skin pigmentation may experience not only higher risks for hypovitaminosis D (and the sequelae of poor skeletal health), but also may be at greater risks for psychological and psychiatric conditions that ensue from decreased vitamin D availability in the brain over time [40] Greater pigmentation of the iris likely could add to the likelihood of SAD by allowing less light to reach the retina resulting in less input to the circadian system [19].…”

A systematic review of light therapy on mood scores in major depressive disorder: light specification, dose, timing and delivery

“…White light is the most widely used source in 21/24 studies. Its effectiveness may be due to the presence of blue and green colours as components of white light [47]. Indeed, the supra-chiasmatic nucleus (SCN) is sensitive to changes in bright light of white, blue and green and change of seasons [12], [23], [34], [39], [41].…”