Isabelle Levent:
Taniguchi, et al. did a systematic review of 54 studies examining how external environments and sunshine exposure affected mental health during the COVID-19 pandemic. The studies spanned the US, China, Korea, and the UK. They found that increased sunlight exposure and time in natural environments positively impacted mental health, with studies showing that access to green spaces and regular outdoor physical activity reduced depression and anxiety symptoms. People who spent more time outdoors in sunlight demonstrated lower rates of depression, while those with low vitamin D levels showed increased depressive symptoms.
Agouti, et al. examine the relationship of vitamin D levels, sun exposure, and generalized anxiety disorder (GAD) among female college students in the United Arab Emirates. They find that sun avoidance habits, due to weather or clothing, and vitamin D deficiency are strongly associated with an elevated risk of GAD. Although their study does not show a direct correlation between Vitamin D intake and GAD, they suggest that increasing vitamin D through diet or sun exposure may decrease anxiety in young women.
Zoya Garg:
https://pmc.ncbi.nlm.nih.gov/articles/PMC10277019/ Positive association between sunlight exposure and mental health existed.
The study demonstrated a significant negative correlation between sunlight exposure and psychological distress, suggesting that increased sunlight exposure improves mental health. Additionally, chronic disease and irregular sleep were strongly associated with poorer mental health. The study emphasizes the importance of natural sunlight exposure for mental well-being, advocating for structural changes in workplaces to increase access to sunlight.
https://norma.ncirl.ie/5687/1/kinginwong.pdf “Sun exposure shows no significant correlation with anxiety or depression among college students, but depression and anxiety are strongly and positively correlated”
The study confirms a strong positive correlation between depression and anxiety levels among students. Wong suggests that while sun exposure is often linked to vitamin D synthesis, its direct impact on mental health remains unclear, and other factors may play a larger role in influencing depression and anxiety among students.
Athena Shiravi:
- https://www.tandfonline.com/doi/epdf/10.1080/19381980.2016.1248325?needAccess=true
- Moderate sun exposure is linked to reduced risks of several diseases, including cardiovascular issues, diabetes, multiple sclerosis, and certain cancers
- Sunlight stimulates vitamin D production, essential for various bodily functions, though benefits beyond vitamin D (e.g., nitric oxide release, serotonin, and beta-endorphins) also contribute to overall wellbeing
- Inadequate exposure is associated with increased risks of all-cause mortality and diseases like Alzheimer’s, metabolic syndrome, and myopia
- Encourages non-burning sun exposure to maintain serum 25(OH)D levels of at least 30 ng/mL while avoiding sunburn to mitigate risks of skin cancer
- Highlights the need for public health messaging to promote balanced sun exposure for holistic health benefits
- https://www.mdpi.com/1660-4601/17/14/5014
- Sunlight positively affects mood and mental health, reducing symptoms of depression, particularly seasonal affective disorder (SAD), because exposure triggers serotonin production, enhancing feelings of happiness and relaxation.
- Supports the immune system and regulates circadian rhythms, contributing to better sleep quality.
- Sunlight exposure has been linked to lower blood pressure through nitric oxide activation in the skin.
Henry Greenman:
Sunlight: Time for a Rethink? https://pubmed.ncbi.nlm.nih.gov/38661623/
Sunlight exposure has long been associated with skin cancer risks, but emerging evidence suggests it also provides significant systemic health benefits. This paper includes epidemiological studies in the UK and Sweden that indicate that increased sun exposure correlates with lower all-cause mortality, particularly from cardiovascular disease and cancer, despite a higher incidence of melanoma. While vitamin D synthesis depends on UVB radiation, numerous clinical trials have found no significant health benefits from vitamin D supplementation, challenging the assumption that supplementation can replace sun exposure. Instead, non-vitamin D mechanisms, such as nitric oxide (NO) release from the skin, appear to lower blood pressure, reducing cardiovascular disease risk. Sunlight may also play a role in reducing myopia, modulating immune function, and lowering the severity of multiple sclerosis (MS) and COVID-19. The seasonal rise in cardiovascular deaths and the increased hypertension prevalence in higher latitudes further support sunlight’s broader health benefits. The current dermatology advice emphasizing sun avoidance may need revision to balance skin cancer risks with the overall mortality benefits of sunlight. The paper recommends that public health recommendations should consider individual skin color and geographical factors, ensuring that policies do not overlook the broader, life-extending effects of moderate sun exposure.
Seasonality of brain function: role in psychiatric disorders https://www.nature.com/articles/s41398-023-02365-x
This study highlights that circadian rhythm disruptions, driven by seasonal variations in light exposure, may contribute to mood disorders such as seasonal affective disorder (SAD), major depression, bipolar disorder, and schizophrenia. It emphasizes that the brain undergoes seasonal fluctuations in neurotransmitter activity, particularly in serotonin and dopamine, which are crucial for mood regulation. Neuroimaging studies show that brain structure and function exhibit seasonal variation, with potential impacts on cognitive processes and emotional stability. The immune system also plays a role in seasonal psychiatric symptoms, with evidence of seasonal variations in inflammation affecting brain function. Additionally, genetic predispositions, chronotype (morning vs. evening preference), age, sex, and geographic latitude contribute to individual differences in seasonal psychiatric symptoms. The study calls for more longitudinal neuroimaging studies with high temporal resolution to understand how light exposure, circadian rhythms, and neurotransmitter dynamics interact to influence psychiatric conditions. Ultimately, the findings suggest that seasonal adaptations in brain function may be crucial for mental health, requiring personalized interventions for those with heightened seasonality-related psychiatric risks.
Emily Hsu:
This study shows that morning bright light (as opposed to office lights) can improve sleep at night and alertness during the day. The study was conducted on 12 postgraduate students who spend an average of 10 hours in the office each day. The researchers first ran a 2-workday baseline study where they measured the participants’ sleep quality with an actigraphy and a sleep diary, in addition to “self-ratings of daytime sleepiness, mood, mental fatigue, perceived effort, and next morning sleepiness.” Then, they ran the intervention study for a 5-day workweek where they introduced 90-minute morning light intervention. The intervention resulted in higher sleep efficiency as measured by the actigraphy. After the 5-day intervention, the researchers also observed an earlier sleep onset time and lower morning sleepiness among the participants. Therefore, this study supports existing research which ties the positive impacts of daylight to sleep.
In this study, researchers measured the sleep timing of 507 UW undergraduate students enrolled in classes over the four seasons from 2015 to 2018. The study found that students were going to sleep later and waking up later during winter – when Seattle gets the least sunlight. For example, the data from the study showed that on school days in the winter, students fell asleep on average 40 minutes later and woke up 27 minutes later than students in the spring. Similarly, on free days, students in the winter fell asleep 46 minutes later and woke up 50 minutes later than students in the spring. This seems counterintuitive because Seattle gets the most daylight hours in the spring/summer, so students should be staying up later. However, researchers attribute this effect to the lack of sun exposure students get in the winter, which impacts their circadian rhythm.
