The Impact of Sun Exposure on Hormones

Vitamin D and Melatonin

Sunlight is not just a source of warmth and light; it also has a profound impact on our hormones, specifically Vitamin D and Melatonin. We are fortunate to live in Calgary, one of the sunniest city in Canada. On average, Calgary has 333 days of sunshine per year and roughly 2400 hours of bright sunshine annually. So, let’s explore how sunlight and sun exposure influences these hormones and how they impact health and well-being.


Vitamin D: The Sunshine Vitamin

Vitamin D, often referred to as the “sunshine vitamin,” is produced in the skin when exposed to sunlight. This vitamin has various functions, including, supporting bone health, boosting the immune system, and aiding in the absorption of calcium. 

Research has suggested that Vitamin D is also involved in hormone regulation. It has been associated with the modulation of insulin; a hormone crucial for blood sugar control [1]. A systematic review and meta-analysis by Pittas et al. (2007) suggested that supplementation of calcium and vitamin D may be beneficial in improving glucose metabolism. However, the studies included were observational studies, so the data is limited. 

Further, Vitamin D may have a role in regulating reproductive hormones such as estrogen and testosterone [2]. However, further studies are needed to fully understand these interactions. According to a systematic review by Lerchbaum and Obermayer-Pietsch on Vitamin D and fertility found that vitamin D receptors and metabolizing enzymes are found in reproductive tissue for both males and females. In mice models, knocking out the vitamin D receptors resulted in severe hypogonadism, decreased sperm count and motility and severe abnormalities of the testes and ovaries [2]. This review also suggested that low Vitamin D levels in poly cystic ovarian syndrome are associated with obesity, insulin resistance and menstrual irregularities. It is important to understand that the research in this area is limited to observational studies which does not control for confounding factors. So further research needs to be conducted to understand the true impact of Vitamin D on hormone health.

While sunlight is a natural source of Vitamin D, it is important to exercise caution. Excessive sun exposure without proper protection can lead to skin damage and increase the risk of skin cancer. It is advisable to strike a balance between safe sun exposure and obtaining Vitamin D from dietary sources such as fatty fish, fortified dairy products, and supplements if necessary.


Melatonin: The Sleep Hormone

Melatonin, often called the “sleep hormone,” is responsible for regulating our sleep-wake cycle and maintaining our circadian rhythm. Sunlight exposure plays a crucial role in melatonin regulation.

When we are exposed to sunlight in the morning, our melatonin production is suppressed, keeping us awake and alert. In contrast, when we wind down at night and reduce our exposure to light in the evening, our body increases melatonin production, preparing us for restful sleep [3].

To optimize melatonin regulation, it is recommended to expose oneself to morning sunlight! Exposure to sunlight within the first hours of waking for a minimum 5-10 minutes in direct sunlight, or 15-20 minutes on overcast days, can have a significant impact on well-being. 

Safe Sun Habits and Hormonal Balance

While embracing the benefits of sunlight, it is essential to practice sun safety. Protect your skin by using a broad-spectrum sunscreen, wearing protective clothing, and seeking shade during peak sun hours. It is s also advisable to consult with a healthcare professional regarding optimal dosing for Vitamin D and Melatonin supplementation.

Achieving hormonal balance requires a holistic approach. In addition to sun exposure, it is essential to prioritize a healthy lifestyle that includes a balanced diet, regular exercise, stress management, and good sleep hygiene. By taking care of your overall well-being, you can optimize the benefits of sunlight on your hormones and maintain optimal health.

Remember, moderation and sun safety are key. Enjoy all the sunshine Calgary has to offer and soak up the positive hormonal health benefits of sun exposure.


How Pregnancy, Hormone Replacement Therapy and Contraceptives May Impact the Skin’s Response to Sunlight

Hormones play a crucial role in various physiological processes within the human body, including the skin’s response to sunlight. Changes in hormone levels, whether due to pregnancy, hormone replacement therapy, or birth control, can impact our skins sensitivity to sunlight. Let’s discuss how hormone fluctuations during pregnancy and changes in hormones through hormone replacement therapy or hormonal birth control, can affect the skin’s reaction to the sun. 

Pregnancy and Skin Sensitivity to Sunlight:

During pregnancy, a woman’s body undergoes a cascade of hormonal changes, including increased levels of estrogen and progesterone. These hormonal shifts can make the skin more sensitive to sunlight, resulting in a heightened risk of sunburn and skin discoloration. This phenomenon is known as pregnancy-induced photosensitivity.

According to a study published in the Journal of the American Academy of Dermatology, pregnancy-induced photosensitivity affects approximately 50-70% of pregnant women [4]. The elevated hormone levels can lead to an increased production of melanin, the pigment responsible for skin color, which can result in the appearance of dark patches on the face known as melasma or the “mask of pregnancy.”

Hormone Replacement Therapy and Skin Sensitivity to Sunlight:

Estrogen and progesterone are commonly prescribed modalities to hormone replacement therapy. Research published in the journal Climacteric suggests that hormone therapy may increase skin photosensitivity due to the presence of estrogen [5]. Estrogen can enhance melanocyte activity and lead to increased pigmentation and sun sensitivity. Consequently, individuals undergoing hormone therapy should take precautionary measures to protect their skin from the sun’s harmful rays.

Contraceptives and Skin Sensitivity to Sunlight:

Oral contraceptives, commonly known as birth control pills, also contain hormones that can potentially impact the skin’s reaction to sunlight. Birth control pills typically contain synthetic versions of estrogen and progesterone, or progesterone alone, which can affect melanin production and skin sensitivity.

According to a study published in the Journal of the European Academy of Dermatology and Venereology, some women using birth control pills may experience increased sensitivity to the sun [6]. This sensitivity can manifest as heightened risk of sunburn, rash, or changes in pigmentation.

To protect the skin, experts recommend:

  1. Applying broad-spectrum sunscreen with a high sun protection factor (SPF) regularly.
  2. Wearing protective clothing, such as wide-brimmed hats and long-sleeved garments.
  3. Seeking shade during peak sun hours, usually between 10 am and 4 pm.
  4. Avoid prolonged sun exposure.

Shelby Sheppard
Nurse Practitioner

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