During the winter, the days get shorter and we spend more hours in the dark. This change not only affects our mood or energy levels, but can also have an impact on the body's natural rhythms, including those that regulate reproductive function.
Although it is not a topic that is often talked about, light – or rather, its absence – plays an important role in hormonal balance and, therefore, in both female and male fertility.
Light and our biological rhythms
Our body works by following an "internal clock" known as the circadian rhythm, which regulates essential processes such as sleep, hormone release, and body temperature. This watch is mainly synchronized thanks to sunlight.
In winter, the reduction in daylight hours can throw this system out of whack. Prolonged darkness stimulates the production of melatonin, the hormone that induces sleep. Although melatonin is beneficial and serves antioxidant functions in the ovaries and testicles, its excess or imbalance can interfere with the hormonal axis that regulates ovulation and spermatogenesis.
Melatonin, sleep and fertility
Melatonin has a dual role. On the one hand, it helps protect reproductive cells from oxidative damage and promotes the quality of oocytes and sperm. On the other hand, if its secretion remains high during the day – due to lack of sunlight or sleep disturbances – it can affect the release of sex hormones such as LH and FSH, essential for ovulation and spermatogenesis.
Therefore, maintaining regular exposure to natural light during daylight hours and respecting nighttime rest schedules are simple but important measures to take care of fertility.
Vitamin D
The synthesis of vitamin D depends directly on sun exposure. In the cold months, when the days are shorter and we spend more time indoors, their levels tend to decrease.
This vitamin plays an important role in reproductive function as it participates in the maturation of oocytes, embryo implantation and testosterone production. It is also related to sperm motility and the presence of regular ovulatory cycles.
How to Counteract the Effects of Winter
- Take advantage of natural light: go outside in the middle of the day, even if it's just for a few minutes.
- Take care of sleep: maintain regular schedules and avoid bright screens before sleeping.
- Assess your vitamin D levels: your doctor may request an analysis and, if necessary, recommend supplementation.
- Include foods rich in vitamin D, such as fatty fish, eggs, and fortified dairy.
- Practice moderate exercise outdoors: improve circulation, mood and hormonal balance.
Winter does not directly affect fertility, but the lack of light can disrupt hormonal balance. Taking care of rest, getting out in the sun, and maintaining adequate vitamin D levels are habits that contribute to healthy reproductive function.
Dr. Cristina Guix
Gynecologist expert in fertility in Barcelona IVF
