Abstract:
Introduction. Blue light [wavelength between 400-495nm], from digital sources and artificial
lighting in the evening, hence inhibit normal secretion patterns of melatonin causing circadian
rhythm and sleep disturbances. There is an inversely proportional relationship between blue
light exposure and melatonin secretion. In the same time, blue light can be absorbed by the
pigmental layer of the retina that contains melanin. Thereby, the quantity of blue light that will
rich the retina can be influenced by the amount of melanin from the eyes.
Aim of the study. The purpose is to appreciate the circadian rhythm and sleep disturbances
and depth of blue light effect on melatonin secretion on different ethnical groups, integrating
skin and eye pigmentation effects on the same matter;
Materials and methods. An analysis of the latest scientific sources has been carried out using
the PubMed search engines, 'HINARI' and Google Academic with the help of keywords: blue
light, ethnicity, skin pigmentation and eye colour, sleep quality, sleep consistency, sleep
duration.
Results. The role of ethnicity in most aspects of human health is well documented. An example
is the inefficiency of certain drugs used in asthma treatment in certain racial groups. Other
studies determined a decrease in prevalence and incidence of Parkinson Disease in Americans
of African descent compared to Caucasians. Also, shorter sleep was reported in black than in
Asian, in Asian than in Hispanic/Latin and in Hispanic/Latin than in White. More sleep quality
disturbance was reported in Black than in Asian and in Asian than in Latin. One of the
explanations of the influence of ethnicity on sleep is the amount of melanin in the eyes. Some
studies have shown that physiological responses to light depend on eye colour and that
intraocular light scattering is higher in blue-eyed Caucasians. The percentage of suppression
of melatonin secretion two hours after the start of light exposure was significantly more
abundant in light-eyed Caucasians than in dark-eyed Asians. In the same time, in a comparative
study which analysed the influence of light treatment in Seasonal Affective Disorder (SAD),
was found that following six weeks of light therapy, African-American participants with SAD
had a lower remission rate than Caucasian participants. Researchers suggested that higher
melanin content of the pupil and retinal pigment epithelium in African-Americans may reduce
the retinal illuminance in African-American SAD patients during light treatment hence
reducing the effect of light therapy. These results suggest that the sensitivity of melatonin to
light suppression is influenced by eye pigmentation and can be related to ethnicity,
respectively.
Description:
Department of Human Physiology and Biophysics, Nicolae Testemitanu
State University of Medicine and Pharmacy, Chisinau, Republic of Moldova, The 8th International Medical Congress for Students and Young Doctors, September 24-26, 2020