Summer Solstice! Welcome Summer!
Multicolored flower that looks like a rainbow on a black background. The flower is the lower right corner of the image.
The summer solstice is so close in the Northern Hemisphere! The summer solstice marks the longest day (longest period of sunlight hours) and shortest night of the year. Many also call this the first day of summer. However, this is dependent on the perspective. Meteorologically the solstice is not the first day of summer, but astronomically it is (Almanac, 2025). This year the solstice happens on Sunday, June 21, at 4:24 A.M. EDT when the Earth is at the point in its orbit where the North Pole reaches its maximum tilt (approximately 23.5 degrees) toward the Sun (Almanac, 2025). This is also the time when the Northern Hemisphere is exposed to the Sun at the most direct angle of the year. This time of year has some profound implications for neurobiology and psychological well-being. These are what we are going to explore in preparation for June 21st!
Circadian Rhythm and Serotonin
Our circadian rhythm is our body’s internal 24-hour clock, found in the suprachiasmatic nucleus (SCN) within the brain. This structure helps regulate our sleep-wake cycles, hormonal balance, memory consolidation, metabolic regulation, and temperature based on light-dark cycles (Desai et al., 2024; Morin, 1999). In other words, SCN helps promote alertness in the morning and melatonin-driven sleepiness at night. When our circadian rhythm is disrupted via exposure to blue light, changes in melatonin and cortisol levels, jet lag, or insomnia we can experience sleep disorders, fatigue, cognitive issues, and it can even increase the risk of chronic diseases like diabetes, obesity, and seasonal affective disorder (Desai et al., 2024).
Now we come to the point. In summer we are exposed to more sunlight which has an impact on our production of serotonin. Human skin, according to research, has an inherent serotonergic system (Sansone & Sansone, 2013). Translation. Our bodies are capable of being exposed to sunshine and making serotonin. Serotonin production in the brain is lower in the winter and higher in the summer due to our exposure to bright sunlight (Lambert et al., 2002). Why do we care? Because serotonin is often called nature’s feel-good chemical, and when we experience higher levels of serotonin we have boosted mood, increased focus, and a better sense of calm (Jauhar et al., 2023; Jenkins et al., 2026). During the summer months, our circadian rhythms are appreciative of the exposure to more natural light and people who have a Seasonal Affective Disorder (SAD) tend to have a lessening of symptoms.
Sleep Hygiene Challenges
While all the amazing light that we are exposed to is great for our moods, as discussed above, it also presents a challenge for sleep. The extended hours of daylight can potentially suppress the production of melatonin, the hormone that helps us sleep (Paul et al., 2015). Remember sleep is important because sleep helps repair and restore the brain, regulates emotions, and consolidates memories. We need our sleep! An additional consideration is how sleep deprivation can trigger anxiety, irritability, and manic episodes for people with bipolar disorder (Gold & Sylvia, 2016; Xue et al., 2025). During the summer months it is important to set boundaries around not using devices at night and minimizing exposure to environmental light by using sleep masks or blackout curtains if possible.
Summer Symbolism
The summer solstice can be thought of as a peak in an annual cycle. It is the peak of summer where we have maximum daylight. This lends itself to a good time to reflect. Here are few questions that you may want to consider exploring for yourself:
What in your life is in "full bloom"?
What have you been nurturing since the winter that is now ready to be celebrated?
There is one other piece of symbolism that we might want to also consider. In cultures where doing and producing is emphasized, much like the sun, we might feel pressured to "burn bright" constantly during the summer. It’s important to remember that peak energy is unsustainable if not balanced with rest and recovery. Nature reminds us of that as we move through the different seasons. Think about fall and winter and how they balance out summer and spring.
Connection and Co-Regulation
When we look from the Polyvagal Theory perspective, the summer solstice and summer provide an excellent opportunity to engage in social engagement. Co-regulation and connection are a fundamental part of Porges’ Polyvagal Theory. This part of the theory addresses how, through a biological process, two nervous systems mutually influence each other to foster safety and calm (Porges, 2022). In Polyvagal language this is called neuroception and occurs via social engagement using voice, eye contact, and touch to help calm stress and shift from a state of fight-or-flight to one of calm. Think about how a caregiver can calm a baby. The mother helps the baby regulate. Now think about how during summer many of us spend more time with friends, family, etc. which helps with social isolation. We spend more time outdoors engaging with our friends, family, and community helping to bring about more of a sense of “Ventral Vagal” safety. The ventral vagal is what Porges identified as the social connection part of the vagal nerve while the dorsal vagal is where our fight-or-flight response comes from.
Finding Grounding in the Heat
The summer energy can sometimes feel “flighty” or ungrounded. It can feel like high sympathetic activation. The heat and the buzzing energy of the season can lead to a sense of being in your head. The key words here are “can.” This may not happen with everyone as we all have different experiences. If this is you, you can practice “Earthing.” With the ground now warm, take your shoes off and put your feet directly on the grass or sand. Feel your connection with the Earth and let any excess energy ground or absorb into the Earth. Then bring your awareness back into your physical body.
take action today moment:
Today's take action moment is simple! Explore some of the suggestions offered in the post.
Learn More About the summer solstice:
Celebrate the Summer Solstice with Reconnection
Could the sun be good for your heart?
References
Desai, D., Momin, A., Hirpara, P., Jha, H., Thaker, R., & Patel, J. (2024). Exploring the role of circadian rhythms in sleep and recovery: A review article. Cureus, 16(6), e61568. https://doi.org/10.7759/cureus.61568
Gold, A. K., & Sylvia, L. G. (2016). The role of sleep in bipolar disorder. Nature and Science of Sleep, 8, 207–214. https://doi.org/10.2147/NSS.S85754
Jauhar, S., Cowen, P. J., & Browning, M. (2023). Fifty years on: Serotonin and depression. Journal of Psychopharmacology (Oxford, England), 37(3), 237–241. https://doi.org/10.1177/02698811231161813
Jenkins, T. A., Nguyen, J. C., Polglaze, K. E., & Bertrand, P. P. (2016). Influence of tryptophan and serotonin on mood and cognition with a possible role of the gut-brain axis. Nutrients, 8(1), 56. https://doi.org/10.3390/nu8010056
Lambert, G. W., Reid, C., Kaye, D. M., Jennings, G. L., & Esler, M. D. (2002). Effect of sunlight and season on serotonin turnover in the brain. Lancet (London, England), 360(9348), 1840–1842. https://doi.org/10.1016/s0140-6736(02)11737-5
Morin, L. P. (1999). Serotonin and the regulation of mammalian circadian rhythmicity. Annals of Medicine, 31(1), 12-33. https://doi.org/10.3109/07853899909019259
Paul, M. A., Love, R. J., Hawton, A., & Arendt, J. (2015). Sleep and the endogenous melatonin rhythm of high arctic residents during the summer and winter. Physiology & Behavior, 141, 199–206. https://doi.org/10.1016/j.physbeh.2015.01.021
Porges, S. W. (2022). Polyvagal theory: A science of safety. Frontiers in Integrative Neuroscience, 16, 871227. https://doi.org/10.3389/fnint.2022.871227
Sansone, R. A., & Sansone, L. A. (2013). Sunshine, serotonin, and skin: A partial explanation for seasonal patterns in psychopathology?. Innovations in Clinical Neuroscience, 10(7-8), 20–24. https://pmc.ncbi.nlm.nih.gov/articles/PMC3779905/
Xue, Y., Wang, W. D., Liu, Y. J., Wang, J., & Walters, A. S. (2025). Sleep disturbances in generalized anxiety disorder: The central role of insomnia. Sleep Medicine, 132, 106545. https://doi.org/10.1016/j.sleep.2025.106545