Post by Pearl Ton, a pre-med undergraduate pursuing a Bachelor of Science in Psychology and minors in both Business Administration and Interdisciplinary Neuroscience at Portland State University.
Hi there! My name is Pearl and I’m a premed student at Portland State University. My major is Psychology while my minors include Interdisciplinary Neuroscience and Business Administration. A fun-ish fact about me is that I have a merle chihuahua that I love very, very much. He is my SUNSHINE.
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One of the first outreach experiences I joined was at Sunnyside Environmental School in Portland Public Schools, which welcomes kids in kindergarten through 8th grade. As I walked around the school, trying to find an entrance, I couldn’t help but notice the beautiful sun and nature all around. Students were all playing outside, and there were so many plants inside the building. I wondered if popular podcaster Andrew Huberman’s constant talk about the benefits of sunlight really has the impact that he claims.
Notice the greenery on the windows!
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Andrew Huberman is a professor at Stanford University. He is well known for his podcast, the Huberman Lab, where he talks about science and research backed tools.
LEARN MORE: Huberman Lab Podcast
Sunlight exposure can help regulate serotonin and melatonin
Serotonin
Serotonin is a brain neurotransmitter and peripheral hormone that stabilizes mood.
Lack of sunlight decreases levels of serotonin, while increasing the risk of depression. Research finds that people who receive less sunlight have a higher likelihood of cognitive impairment, including the ability to think clearly, remember and make decisions.
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Serotonin carries important messages between neurons in the brain. The cell bodies of these neurons are located in the raphe nuclei in your brainstem, but the neurotransmitter is released from their axon terminals in many areas, including the prefrontal cortex.
Curiously the vast majority of serotonin (about 95%!) is released outside the brain as a hormone – in your gut! I know that my gut powerfully influences how I feel. Perhaps this is why when sunlight is lacking, our entire body reacts and responds.
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Seasonal Affective Disorder
This is very true here in the Pacific Northwest! With limited winter sun, people can experience Seasonal Affective Disorder (or SAD), and have low mood, irritability, and a loss of interest in social activities. Light exposure has a big positive impact, reducing SAD symptoms. If you experience SAD, please go and bask in the sun (or a therapy lamp)!
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Melatonin
Low sunlight exposure also negatively impacts the regulation of melatonin.
Back in the day, humans were less advanced in terms of technology and had to depend on the sun for their daily activities. We couldn’t do much once the sun was down besides sleep, and we also spent lots of time outside in sunlight every day. However, once electricity was discovered and lighting technology advanced, we could do pretty much anything anytime. This may sound like a great thing, and in many ways it is, but it is also potentially harmful if we aren’t careful.
Blue light can make you more alert and enhance cognitive function. Again, this sounds good doesn’t it? Well, not always. Imagine trying to sleep when your brain is more alert.
Melatonin is a hormone involved in promoting sleep and has a huge impact on our sleep/wake cycle, or circadian rhythm. Melatonin is actually synthesized from serotonin and sunlight (particularly blue light) exposure prevents its release from the pineal gland on the back (or dorsal surface) of our brainstem.
Blue light and other kinds of light at night can disrupt one’s circadian rhythm.
If there is not enough sunlight exposure in daytime, too much melatonin can be synthesized and impact our circadian rhythm. Blue light in the evening (from phones, or other screens) can also inhibit melatonin release, making it more difficult for us to go to sleep. Putting all the screens away early can help!
LEARN MORE: What is melatonin and how does it work?
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Can too much blue light even…kill us?!
I found one study reporting that daily blue light exposure shortens lifespan and causes brain neurodegeneration in flies! The light interferes with sleep and circadian disorders. Sleep is when the brain cleans and repairs itself, so without good sleep, the brain and body can become unwell and function poorly. There is a reason why sleep deprivation is one of the worse torture methods.
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Light in Astoria
Below is a picture from a sunny spring day in Astoria, Oregon! Beautiful isn’t it?
We had a great time in Astoria and loved all the curious kiddos we met during outreach.
One kid asked us “where did brains come from?”…
…and we all had to stop and momentarily re-evaluate our existence.
We brought up evolution and started getting philosophical but the kid was actually asking about the real human brain specimens that we’d brought for them to see and touch in the back of the room. Phew! Did not know how I was going to answer that question at first.
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What about working nights?
Those who work night shifts are on average unhealthier than those who work in the day.
Although there are other factors that contribute, lack of sunlight is for sure one of the major ones. Sunlight helps regulate sleep and our circadian rhythms so night shifters are more sleep-deprived, and thus more vulnerable to neurological disorders including strokes, epilepsy, Alzheimer’s and Parkinson’s disease. Eating at night also alters metabolism, and decreases our ability to process blood sugar.
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Want to avoid worsening myopia? Get some SUN!
Myopia is a condition in which people can see things close to them clearly but objects farther away appear blurry. This happens because of the shape of our eyes; more specifically, with myopia, the eyes are elongated forwards. Nowadays, everyone is on their phones and electronic devices, especially younger generations.
Constantly looking at near objects (phones, or books) indoors, away from sunlight, actually makes our eyeballs grow longer, and the incidence of myopia is going up!
Outdoor light exposure can help prevent further elongation, with the most effective time at least two hours (preferably more) per day. Scientists think that sunlight prevents or slows eye elongation because sunlight provokes retinal dopamine release, which inhibits changes in the shape of the eye.
“…studies have found that sunlight induces dopamine release from the retina, prevents eyeball enlargement, and inhibits axial elongation. If light deprivation and low ambient illuminance inhibited the dopamine receptor in chicks, axial elongation will not be inhibited, and myopic changes will increase…”
— Ciao-Lin Ho, Wei-Fong Wu, and Yiing Mei Liou
Myopia diagnoses are increasing. Be mindful and help children keep their eyesight clear so that they don’t need to depend on glasses. Take them to the park. Or go for a hike. Or enjoy a picnic.
LEARN MORE: Dose–Response Relationship of Outdoor Exposure and Myopia Indicators
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Go outside!
Moral of the story is….go outside and get some RAW sunlight!!!
(but limit your blue light at night 🙂