Brushyour phone before bed is prone to depression? Xue Tian/Zhao Huan reveals the nerve mechanism of night-time blue light "de-depression".

In addition to producing vision, inature also regulates various physiological functions, including mood.it is well known that phototherapy during the day has antidepressant effects. However, it has been reported that excessive exposure to light at night can lead to depressive symptoms, and the neural mechanism underlying the effects of light differences between day and night remains unclear.on June 1, 2020, Xue Tian of University of science and technology of China and Zhao Huan of Hefei University jointly published the title "a circular RH gated subcortical pathway for nighttime light induced depressive like behaviors in nature neuroscience In this study, we used an example of mouse nighttime illumination (LAN) to show that Lan induces depressive behavior without interfering with circadian rhythm.this effect is mediated by a neural pathway from ganglion cells expressing retinal melanin to dorsal nucleus (dphb) of lateral habenular nucleus to nucleus accumbens (NAC).importantly, dphb is controlled by circadian rhythms and is more easily activated at night than during the day.this suggests that the iprgc → dphb → NAC pathway preferentially transmits light signals at night, thus mediating LAN induced depression like behavior.these findings may be significant when considering the impact of industrial general nighttime lighting on mental health.light is essential for most species, including humans.in addition to its obvious role in visual production, light can also regulate a variety of physiological functions, such as biological rhythm, sleep and wake-up, cognition and emotion.in a typical "day time", animals may be exposed to continuous light for about 12 hours.in humans, phototherapy has antidepressant properties, while nighttime lighting may have a negative impact on mood.exposure to excessive nighttime lighting before bedtime (whether it's "natural lighting" or the use of electronic devices such as mobile phones or personal computers) carries a greater risk of depressive symptoms.in different circadian rhythm stages, these contradictory effects suggest that exposure time may be a key factor.the understanding of the neural mechanism behind this obvious paradox is the basis for our understanding of light regulating emotion, but it remains to be clarified.for mammals, light is an effective inducer of circadian rhythm.therefore, light can indirectly affect emotions through the regulation of circadian rhythm system.previous studies have shown that some forms of LAN can disrupt circadian rhythms at both molecular and physiological levels. however, a number of evidences further suggest that there is a direct neural pathway through which light can regulate emotional behaviors that are not related to the deterioration of circadian rhythm. } the study proposed a neural pathway (picture from Nature Neuroscience) of depressive behavior caused by increasing light at night. Light perception in mammals is mainly realized by retinal photoreceptors. in addition to the imaging rod cells and cone cells, there is a third group of photoreceptors in the retina: intrinsic photoreceptor retinal ganglion cells (iprgc), which can regulate non imaging vision. they use melanin to detect light with the highest sensitivity to blue light (about 480 nm wavelength), and transmit information related to environmental irradiation to multiple subcortical nuclei. this study used an example of mouse nighttime illumination (LAN) to show that Lan induces depressive behavior without interfering with circadian rhythm. this effect is mediated by a neural pathway from ganglion cells expressing retinal melanin to dorsal nucleus (dphb) of lateral habenular nucleus to nucleus accumbens (NAC). importantly, dphb is controlled by circadian rhythms and is more easily activated at night than during the day. this suggests that the iprgc → dphb → NAC pathway preferentially transmits light signals at night, thus mediating LAN induced depression like behavior. these findings may be significant when considering the impact of industrial general nighttime lighting on mental health. reference message: