The Summer Sun's Calling My Name: the Importance of Light, Serotonin and Melatonin.
- May 18, 2023
- 5 min read
Updated: Jul 24, 2023
For those of us who live in areas like the Midwest, we are finally getting to those seasons that allow us to be outdoors in the light for extended periods! And, if you are anything like me, you are now anticipating
an overall sense of better well being. I remember when I was a kid, the advent of summer was always associated with the bliss of long hours playing outdoors in the sun, followed by a "dead to the world" deep sleep, as I passed out within two seconds of hitting the pillow! Even now as an adult, springs and summers are
associated in my mind with good health. In part, this may be due to the fact that I am not as likely to be isolated at home, and I get to do enjoyable outdoor activities like kayaking, working in the garden, or taking a walk. But, maybe these improvements in mood, sleep, and my overall sense of well being in the summer months are more than that?? Perhaps there are some things about being in the sunshine that actually afford us good health.....
Serotonin and Melatonin
So, let's talk first about serotonin. Serotonin is a neurotransmitter that mostly affects the brain and spinal cord but has also been found to impact other organs and tissues throughout the body. Neurotransmitters like serotonin allow the nerves of the body to conduct signals and communicate with each other--they tell the body how to function.
Serotonin is often referred to as "the happy neurotransmitter", as it is known to help regulate our mood. It impacts depression and anxiety and even our social behaviors, such as whether we choose to isolate ourselves or connect with people, and our tendency for irritability, agitation and anger. The impact of serotonin on mood has been well known to pharmaceutical companies for decades. Thus, the major treatments for depression have emphasized trying to keep serotonin in circulation for longer periods of time before "re-uptake". Unfortunately, like most things that change the body's natural response, the body will often adapt to these medications, which means decreasing efficacy over time, and decreased overall production of serotonin.
Serotonin is also known to have significant impact on fatigue, sleep, appetite, memory, digestion and sexual function. This makes sense, as when we are depressed, we also experience changes in appetite, energy level, sleep, concentration, and sexual desire and function.
Ninety percent of the body's serotonin is produced in the gut: one more reason why gut health is essential to wellness! The brain produces the remaining ten percent of the body's serotonin, and this production is cued or stimulated when natural light (the sunshine) hits the receptors in the retina of the eye. The greater the sunlight, the greater the serotonin production. This makes sense for people who experience true seasonal depression in the darker months of the year.
Serotonin is also critical, because it is the pre-cursor for the production of melatonin (which means, "not enough serotonin= not enough melatonin"). Melatonin is an important hormone that signals the brain when it is time to sleep and allows us to achieve deep, restorative rest (getting to the deeper stages of sleep and remaining in those stages for sufficient periods).
Cortisol and Melatonin
If you are familiar with the science related to health at all, you likely have heard about cortisol. Cortisol is your body's primary stress hormone. While that sounds 100% bad, it is not really so. Cortisol is important in order to "stress your body enough" that you are able to accomplish the things that you need to in a day's time, or to respond to particularly stressful physical (illness) or emotional challenges (worrying about a sick family member). Cortisol is naturally high in the morning, to stimulate you to get out of bed, and it then decreases at the end of the day, just when melatonin is increasing in order to help you fall asleep. Similar to serotonin, sunlight levels affect melatonin levels, but in the opposite way: melatonin release is blocked in response to the sunlight and is stimulated by darkness.
Healthy stress levels and healthy sleep patterns require cortisol and melatonin to work well together, maintaining a very delicate balance throughout the day: As melatonin increases to promote sleepiness, cortisol must then decrease, to lower the body's "stress or readiness response" that "stirs up the tissues and keeps us going". One study found that poor sleep (which can be associated with poor melatonin cycling or production), resulted in a 30% increase in nighttime cortisol (when cortisol should be low)and a 200% increase in the body's free cortisol throughout the day! https://pubmed.ncbi.nlm.nih.gov/24823456/ Because these chemicals work in opposition to each other, melatonin can also play a role in decreasing the oxidative or cellular stress caused by high cortisol levels and is also considered a helpful adjunct for the management of anxiety (emotional stress). During COVID, melatonin was prescribed by many providers to counteract the high levels of cellular oxidative stress known to occur with COVID infection.
Factors that Increase our Levels
As we discussed above, serotonin is produced in part, and released, in response to our exposure to real, natural sunlight. It is also possible to boost serotonin levels with exercise. Some of the current research is focusing on specific gut bacteria which are responsible for maintaining our serotonin levels (remember, that is 90% of our overall serotonin). https://newsroom.ucla.edu/releases/serotonin-prozac-gut-microbiota#:~:text=Hsiao%20and%20her%20research%20group%20reported%20in%20the,to%20gut%20cells%20to%20increase%20production%20of%20serotonin.
Serotonin itself cannot be obtained from our food, but it is produced from tryptophan, an essential amino acid that is obtained from a good, healthy diet. Tryptophan is actually converted to a chemical called 5-HTP, which is then converted to serotonin. 5-HTP has been shown to increase overall serotonin levels when used as a supplement, however, many of the sources of 5-HTP, obtained from an African shrub, have frequently been found to be contaminated. It is recommended that, if supplementing 5-HTP, you make sure that you are using a quality supplement that has been tested, and are doing so in consultation with a medical professional.
Melatonin, again, is produced from serotonin (in the pineal gland of the brain and in the gut), but melatonin can also be obtained per good healthy nutrition, or in supplement form. Tryptophan is dependent upon B6 for synthesis. In other words, if one is deficient in vitamin B6, the body will be unable to effectively convert tryptophan to serotonin, which then will also impact serotonin's conversion to melatonin.
Take Aways
1. Get outside to enjoy the sunlight. Walking or exercising outdoors is even better for increasing serotonin levels.
2. Emphasize good healthy nutrition, foods high in tryptophan or melatonin. (Tryptophan-->5HTP-->Melatonin).
3. Consult your doctor regarding whether supplementation with melatonin might be beneficial for insomnia, or high levels of oxidative or emotional stress.
4. Make sure you are getting adequate levels of B6, as this vitamin is necessary for the conversion of tryptophan to serotonin!
Disclaimer: This BLOG is for Educational Purposes, Only. This information provided is educational and informational in nature and is made only as general information. The information does not establish a patient-provider relationship, establish a standard of care, or offer medical, dietary, or therapeutic care, advice, opinion, diagnosis, or treatment. This information does not replace independent professional or medical judgment and should not be relied upon as medical, psychological, or other professional advice of any kind or nature whatsoever. This information should not be used for diagnosing or treating any mental or physical health problem or disease. You are solely responsible for any action taken based on your interpretation of this information and you are responsible for your own health care decision-making by obtaining any necessary consultations with appropriately licensed health care professionals such as physicians and psychologists.
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