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Sunlight, Mood and Longevity2024-08-26

One of the most interesting biological mechanisms in cells and organisms, including humans, is the circadian clock. This is a cascade of genes that are turned on primarily by sunlight, but also by food and temperature, and regulate the levels of activity of an organism. In most organisms (there are exceptions in nocturnal organisms), they ramp up activity in sunlight, during the day, and during seasons with longer daylight like summer, and conversely shut down activity during dark, at night, and in seasons with shorter daylight like winter, all the way to hibernation. Thus, there are higher levels of activity when the environment is safe and favorable, and lower levels when the environment is less favorable and safe.

One of the key serendipitous discoveries (and subsequent body of work) my teams have made over the last two 25 years have been in establishing that circadian clock genes and mechanisms are core to the biology of mood^{1 2}, which makes sense adaptively and evolutionarily. Mood is a normal adaptive function, it is energy and activity. In mood disorders (depression, bipolar), the levels of activity (mania) or inactivity (depression) are excessive and/or disconnected from the favorability or adversity of the environment. Seasonal affective disorder is another example of an exaggerated response. I often recommend to my patients light therapy and judicious vacations in the sun in the fall and winter months. Lithium and other mood stabilizers are key modulators of the expression of these circadian clock genes, which may explain at least in part how these medications work.

Another key serendipitous discovery we made over the last decade is that mood correlates with longevity, from worms to humans³. Our Life x Mind app helps people keep track of mood, life activities, and provides an active longevity score. It will be very interesting to study in depth the relationship between sunlight, dopamine, mood, and active longevity. That is what we plan to do in the future. It may explain why people seem to live longer in sunny places. Had the architect Frank Lloyd Wright lived only at Taliesin East (in Wisconsin) and not also at Taliesin West (in Arizona), it is improbable he would have lived till age 91.

Footnotes

1. Niculescu, A. et al. Identifying a series of candidate genes for mania and psychosis: a convergent functional genomics approach. Physiological Genomics 4, 83-91 (2000). ↩

2. Le-Niculescu, H. et al. Convergent functional genomics of genome-wide association data for bipolar disorder: comprehensive identification of candidate genes, pathways and mechanisms. Am J Med Genet B Neuropsychiatr Genet 150B, 155-181, doi:10.1002/ajmg.b.30887 (2009). ↩

3. Rangaraju, S. et al. Mood, stress and longevity: convergence on ANK3. Mol Psychiatry 21, 1037-1049, doi:10.1038/mp.2016.65 (2016). ↩