How the Seasons Affect Our Hormones

Understanding how our hormones change with the seasons is a fascinating aspect of how the human body is influenced by natural phenomena, such as daylight, temperature, and seasonal activities. Our body’s response to seasonal changes is deeply connected to hormonal fluctuations, which can influence mood, reproduction, energy, sleep, and even appetite. Below are some key hormones that are influenced by seasonal changes and how they affect the body:

1. Melatonin

What It Does: Melatonin regulates the sleep-wake cycle and is primarily produced in response to darkness.

·      Seasonal Effect: During winter, with shorter daylight hours, the body produces more melatonin, which can lead to increased feelings of sleepiness and fatigue. This explains why people often feel more tired and have lower energy levels in the winter.

·      Impact: Higher melatonin levels in winter may contribute to conditions like Seasonal Affective Disorder (SAD), a type of depression linked to the lack of sunlight.

2. Serotonin 

·      What It Does: Serotonin is a neurotransmitter that influences mood, appetite, and sleep.

·      Seasonal Effect: Sunlight boosts serotonin levels, which is why people tend to feel happier and more energetic in the summer. In contrast, reduced sunlight during fall and winter can lower serotonin levels, leading to mood changes and sometimes contributing to SAD or "winter blues."

·      Impact: Low serotonin levels in winter can affect emotional well-being and sleep patterns, contributing to feelings of depression, irritability, and carbohydrate cravings.

3. Cortisol

·      What It Does: Cortisol is the body’s primary stress hormone, affecting metabolism, blood sugar, and immune function.

·      Seasonal Effect: Cortisol levels can fluctuate with the seasons, often being higher in the winter and lower in the summer. This may be due to factors like reduced daylight, colder temperatures, and the body’s need to conserve energy in winter.

·      Impact: Higher winter cortisol levels may lead to increased stress and a heightened immune response, while lower summer levels contribute to more relaxation and vitality.

4. Testosterone

·      What It Does: Testosterone, found in both men and women, is a hormone responsible for muscle mass, libido, and energy levels.

·      Seasonal Effect: Research suggests that testosterone levels in men tend to peak in late fall and are lowest in the spring. Sunlight, physical activity, and even the body’s need for warmth may influence these fluctuations.

·      Impact: Higher testosterone levels in fall may coincide with increased physical energy and libido. In women, seasonal testosterone changes are less well-documented but are thought to follow similar patterns due to circadian and environmental rhythms.

5. Thyroid Hormones (T3 and T4)

·      What They Do: Thyroid hormones control metabolism and energy levels.

·      Seasonal Effect: The body often requires more energy to stay warm in the winter, leading to increased production of thyroid hormones. In warmer months, thyroid activity may slow down as the body doesn’t need as much energy for thermoregulation.

·      Impact: Higher thyroid hormone levels in winter may help boost metabolism and maintain body temperature, while in summer, the body conserves energy by reducing thyroid activity, resulting in a slower metabolism.

6. Prolactin

·      What It Does: Prolactin is involved in reproductive functions, lactation, and immune regulation.

·      Seasonal Effect: Prolactin levels tend to be higher in winter, especially in women. The increase may be linked to lower sunlight exposure and melatonin levels.

·      Impact: Higher prolactin levels can suppress reproductive function and may contribute to the lower libido seen in winter months.

7. Leptin and Ghrelin

• What They Do: Leptin regulates hunger and fat storage, while ghrelin stimulates appetite.

• Seasonal Effect: During colder months, leptin levels may increase as the body tries to conserve energy and fat, while ghrelin may rise in the winter, increasing hunger. People tend to eat more and crave carbohydrate-rich foods, possibly as a survival mechanism.

• Impact: These changes can lead to weight gain in the winter and decreased food intake in the summer, when energy needs are lower and activity levels higher.

8. Vitamin D (though not a hormone, it acts like one)

·      What It Does: Vitamin D is critical for bone health, immune function, and mood regulation.

·      Seasonal Effect: Vitamin D production in the body is directly influenced by sunlight exposure. In winter, with reduced sunlight, people often experience a drop in vitamin D levels.

·      Impact: Low vitamin D levels can lead to weakened bones, decreased immunity, and mood disturbances, including increased risk of depression and SAD.

How Seasonal Hormonal Changes Affect Humans

• Mood and Mental Health: The decrease in serotonin and increase in melatonin during the winter months are linked to SAD, while the increased sunlight in spring and summer boosts mood and energy.

• Sleep: Melatonin levels rise in winter, leading to longer sleep durations, while in summer, people often experience shorter, more disrupted sleep.

• Metabolism: Seasonal shifts in thyroid and cortisol levels influence metabolism, with higher metabolic rates in winter to keep the body warm, and a slower metabolism in summer.

• Appetite and Weight: Changes in leptin, ghrelin, and serotonin contribute to increased appetite in winter, often leading to winter weight gain, while in summer, people may feel less hungry and more active.

Traditional Chinese Medicine (TCM) acknowledges the influence seasonal changes have on our health and wellbeing. For example, the Five Elements (also known as the Five Phases) are a fundamental framework used to understand the interactions and relationships between the body, nature, and the universe. These elements are Wood, Fire, Earth, Metal, and Water, and they represent different qualities, processes, and phases of transformation in the natural world. Each element is associated with specific organs, seasons, emotions, and other aspects of life. The Five Elements theory explains how different aspects of the body and environment interact and influence one another in a dynamic, cyclical process.

In summary, the Five Elements theory is a dynamic system in TCM that helps us to understand the complex relationships between the body, environment, emotions, and the seasons. It guides diagnosis and treatment, with the goal of maintaining balance and health.

 By Cassandra