The sun and your hormones: vitamin D, melatonin and circadian rhythm in summer

Summer invites us to enjoy longer daylight hours, outdoor activities and holidays. However, this season also involves an important shift for our body.

Sun exposure, higher temperatures and disrupted schedules directly influence our hormonal system, our rest and our energy.

At SHOMMA we understand that hormonal health does not depend solely on oestrogens or progesterone. Hormones such as melatonin, together with vitamin D and a proper circadian rhythm, play a fundamental role in physical and emotional wellbeing, especially during perimenopause and menopause.

What is the relationship between the sun and hormones?

Our body functions according to an internal biological clock known as the circadian rhythm.

This system regulates essential functions such as sleep, body temperature, hormone production, metabolism, energy and immune response.

The main signal that synchronises this clock is sunlight.

When natural light reaches our eyes during the first hours of the day, the brain interprets that the day has begun and sets in motion a complex hormonal cascade that influences virtually the entire body.

Vitamin D: far more than bone health

Although known as "the sunshine vitamin", vitamin D actually behaves like a hormone. Its production largely depends on the skin's exposure to ultraviolet B (UVB) radiation.

We now know it is involved in many processes related to female health:

• Promotes calcium absorption and helps maintain strong bones.
• Supports the immune system.
• Helps preserve muscle function.
• Influences mood regulation.
• Is linked to cardiovascular and metabolic health.

During menopause, when oestrogen levels decline and the risk of bone loss increases, maintaining adequate vitamin D levels becomes even more important.

Melatonin: the hormone that regulates rest

Melatonin is known as the sleep hormone. Its production rises as ambient light decreases, preparing the body for rest.

In summer, longer days and greater light exposure in the evening can delay its release, making it harder to fall asleep or maintain restorative rest.

In addition, many women in perimenopause and menopause already experience sleep disturbances related to hormonal changes, such as night awakenings, hot flushes or poor-quality sleep.

When melatonin production is altered, physical recovery, memory, mood, metabolism and appetite regulation can also be affected.

Sleeping well is not just resting. It allows the body to repair tissues, regulate hormones and maintain metabolic balance.

The circadian rhythm: the great conductor of our health

Every cell in the body follows an internal clock. When that clock works well, our hormones function in a coordinated way.

In summer, however, it is common to shift sleep, meal and exercise schedules. Although these changes are part of enjoying the season, sustaining them for too long can disrupt the circadian rhythm and lead to:

• Greater fatigue.
• Appetite changes.
• Metabolic disturbances.
• Poorer sleep quality.
• A greater sense of stress.

In women with perimenopause or menopause, these small imbalances can intensify symptoms already present.

How to care for your hormones during summer

It is not about avoiding summer, but about helping your body adapt. A few habits can make a real difference:

Seek natural light in the morning. Exposure to sunlight during the first minutes of the day helps synchronise the biological clock and supports proper melatonin production at night.

Protect your rest. Keep sleep schedules as regular as possible, even on holiday. Sleeping well remains one of the pillars of longevity.

Enjoy the sun responsibly. Moderate sun exposure supports vitamin D synthesis, but should always avoid peak-radiation hours and follow photoprotection guidelines.

Stay active. Walking, strength training or exercising outdoors in the first hours of the day helps regulate the circadian rhythm and supports hormonal balance.

Care for your nutrition. A diet rich in quality protein, fruits, vegetables, healthy fats and magnesium-rich foods supports the nervous system and hormone production.

Hormonal health also changes with the seasons

At SHOMMA we understand that hormonal wellbeing does not depend on a single blood test or a single hormone.

Female health is the result of multiple systems working in coordination: sleep, nutrition, physical activity, stress, vitamin D, melatonin and circadian rhythm are all part of that balance.

Understanding how your body responds at each stage of life makes it possible to design personalised strategies to improve energy, rest and quality of life.

Because caring for your hormones also means learning to listen to your body's natural rhythms.

Learn how your body is really working

At SHOMMA Healthspan Center we carry out a comprehensive assessment of female health that includes biomarkers, hormonal status, body composition and lifestyle habits, to help you understand what your body really needs.

Because prevention begins long before symptoms appear.

Scientific references

• Holick MF. Vitamin D Deficiency. New England Journal of Medicine. 2007;357:266-281.
• Arendt J. Melatonin and the Mammalian Pineal Gland. Chapman & Hall.
• Czeisler CA, Buxton OM, Khalsa SBS. The Human Circadian Timing System and Sleep-Wake Regulation. Cold Spring Harbor Perspectives in Biology.
• Endocrine Society. Clinical Practice Guideline: Evaluation, Treatment, and Prevention of Vitamin D Deficiency.