Sunlight not only boost serotonin, but it also improves mood. Serotonin is a brain neurotransmitter.
In a previous article, we saw that serotonin production decreases with age and that low serotonin may be a possible cause of poor sleep. In this article, we look at one way of improving serotonin production via sunlight exposure. And when more serotonin is produced during the daytime, you have more of it available to convert to melatonin at night. Melatonine is the sleep hormone and is converted from serotonin via two enyzmes whose activity increases with darkness …
acetyltransferase) which converts the serotonin to N-acetylserotonin, and HIOMT (hydroxyindole-O- methyltrasferase) which trasfers a methyl group from S-adenosylmethionine to the 5-hydroxyl of the N-acetylserotonin.” [reference]
That is why you need darkness in order to stimulate this conversion. Turn off or dim lights after sunset if you want to sleep better.
You want good sufficient serotonin levels during the day, and good sufficient melatonin levels at night. Serontonin levels can be increased with exposure to sunlight (or alternatively, bright lights during the day).
Healthline writes …
“Exposure to sunlight is thought to increase the brain’s release of a hormone called serotonin. This is associated with boosting mood and helping a person feel calm and focused. At night, darker lighting cues trigger the brain to make another hormone called melatonin. This hormone is responsible for helping a person feel sleepy and go to sleep. Without enough sunlight exposure, a person’s serotonin levels can dip low.”
Low light levels and low serotonin can be a cause of seasonal affected disorder (SAD) which occurs more frequently during winter. That is why sunlight and light therapy boxes can help with SAD and depression. Of course direct sunlight is best. But for those in locations of low sunlight during winter, light therapy boxes can help.
Other factors that can affect serotonin are gut microbiome. 90% of the serotonin is produced in the gut and bacteria in the gut is thought to play a role in this production. [reference]
Not only is sun exposure necessary to reset and strength the circadian rhythm, the light dark contrasts in the 24-hour cycle also stimulates melatonin production.
Dr. Mercola writes …
” Your pineal gland produces melatonin roughly in approximation to the contrast of bright sun exposure in the day and complete darkness at night. If you are in darkness all day long, it can’t appreciate the difference and will not optimize your melatonin production. More sunlight exposure is required as you age.”
There is a direct nerve connection from the retina of your eyes to the suprachiasmatic nucleaus in hypothalamus in your brain. Afterall, it is situated directly above the optic chiasm. The suprachiasmatic nucleaus is responsible for controlling the circadian rhythms and gets its cue from light exposure from the eye.
Wikipedia writes …
“The SCN receives inputs from specialized photosensitive ganglion cells in the retina, via the retinohypothalamic tract. Neurons in the ventrolateral SCN (vlSCN) have the ability for light-induced gene expression. Melanopsin-containing ganglion cells in the retina have a direct connection to the ventrolateral SCN via the retinohypothalamic tract.”
From the book The Brain’s Way of Healing, you find it says …
“Serotonin, a brain neurotransmitter, is known to be low in some depressions; studies show that normal sunlight causes the body to release serotonin”
Later on, the book writes how important natural light is …
“… our indoor spaces are ever more deprived of natural light, in ways we cannot perceive, because the counterfeit light we use is often not composed of the frequencies that preserve life. We need full-spectrum light not just for elegant atriums and lobbies for show, but for everyday living and work spaces. The damage caused by living a light-impoverished life is hidden. … we require light to flourish.”