Seasonal Science Explains Human Vulnerabilities 

Do you have a similar lifestyle routine day after day, month after month? New research shows that this could be detrimental to your health. 

In a study in the world’s most prestigious journal, Nature, researchers at Stanford University identified over 1,000 microbial and molecular seasonal variations in 105 humans over four years, suggesting much of our health and longevity depends on our connection to the seasons.¹ 

This research may explain why people have more allergies in spring and higher blood pressure in winter, stronger immunity in winter, and a 25% increased rate of dying in winter compared to summer.¹ 

The study saw seasonal patterns in a wide range of health factors: in inflammation, immunity, and cardiovascular health, as well as in neurological and psychiatric conditions. They also saw dramatic seasonal shifts in molecules and microbes that explain seasonal patterns related to insulin sensitivity and blood sugar regulation.¹ 

Yes, We Are Seasonal Beings 

According to Ayurveda, we are seasonal beings and our survival depends on living in sync with seasonal cycles. In past articles, I have written about how the enzyme amylase, which digests starch and grain, increases in fall, when there is an abundance of starch harvested. In spring, when little starch is available, amylase wanes.²  

Ayurveda tells us digestive strength is stronger in winter in order to break down denser foods. This has been backed up by studies finding the parasympathetic or rest–and–digest nervous system increases each winter with the onset of colder weather.³ 

Microbes shift in the soil from season to season and unique species adhere to each food, shifting our microbiomes. We now know the human microbiome is designed to shift seasonally.⁴ Microbes like Bacteroidetes increase in summer to support carbohydrate digestion, while Actinobacteria increase in winter to better break down fats and fiber.⁵ 

Neurotransmitters such as serotonin, dopamine, and brain-derived neurotrophic factors (BDNFs) are light sensitive, supporting mood more effectively in lighter summer months and less well during darker winter months, when depression is more common.  

Ayurvedic herbs that support mood stability and BDNFs, such as ashwagandha, turmeric, and bacopa, are fall-harvested roots that support us best in winter.⁶ Melatonin also supports mood stability in winter, naturally surging in darker months to make up for the lack of mood-supportive neurotransmitters that are more light sensitive.⁷ 

Overview: Understanding the New Circadian Science 

1. HbA1c blood sugar tests, which measure three-month average blood sugar, show peaking blood sugar in spring/summer and declining blood sugar in winter. This may be related to increased carbohydrate harvesting in summer.¹ 
2. PER1, belonging to a family of genes that is the primary circadian rhythm pacemaker in the mammalian brain, also shows the highest expression in spring. Emerging evidence suggests deregulation of circadian rhythms (PER1 gene) plays an important role in the development of mammalian cancer. Tumor production has is most active in spring, showing the importance of spring cleansing and a lifestyle in sync with circadian clocks.¹ 
3. Molecular and microbial shifts that boost immunity were found to surge in winter, when greater immunity is required. Populations of immune-enhancing microbes in both the gut and nose increase in winter.¹ 
4. Knee and joint inflammation and arthritic pathways are elevated in spring/summer, during what Ayurveda calls kapha and pitta season, when inflammation is greatest.¹ 
5. Lymph and glandular congestion, causing dry eyes and mouth, is higher in winter, during what Ayurveda calls vata or dry season.¹ 
6. The hibernation gene, SERPINC1, overexpresses in winter compared to summer. For us, that means: get more rest in winter, when days are short, and be more active in summer, when the days are long.¹ 

Did you realize how important it is to honor the fact that we are seasonal beings? How do you live in sync with seasonal changes? Let us know in the comments below. 

See also Methylation-Balancing Foods to Support Healthy Aging