It may seem like hair grows faster in summer, but it’s not that simple
Every summer, it feels like hair grows faster: bangs seem longer, and the ends need trimming. Many people attribute this to the sun and warmth, considering it a natural seasonal response of the body. In reality, research shows that hair follicles barely respond to the change of seasons. But why do we get the opposite impression? What actually triggers hair growth, and how many centimeters does it really add per month?
How the Season Affects Hair Growth Rate
The idea that sun and warmth speed up the appearance of new hair strands sounds logical. Theoretically, exposure to sunlight and temperature could affect blood circulation in the scalp and seasonal hormonal fluctuations. But as board-certified dermatologist Elizabeth Bahar Houshmand notes, in reality, things work differently. This was discussed on the Popular Science website.
In dermatology, it is generally accepted that hair growth is controlled by the biology of the follicle itself, overall health, and complex signaling pathways in the body. No convincing scientific evidence that summer sun specifically makes hair grow longer has been found to date.
The external environment also matters, but more in a negative way. Various airborne pollutants can damage the protective barrier of the scalp and cause inflammation, interfering with normal hair development.
The Effect of Vitamin D on Hair Growth
The main argument of proponents of active hair growth in summer is the increased production of vitamin D under the influence of ultraviolet light. Indeed, this element is important, but here lies the main misconception about physiology.
If a person has a significant vitamin D deficiency, replenishing it will indeed help stop hair loss and restore the process to normal as part of a comprehensive treatment. However, an extra dose of vitamin from summer sun will not make hair grow faster in those whose levels are within the normal range. The body does not accumulate this effect in the form of bonus centimeters on the head.
What Actually Affects Human Hair Growth
Each hair follicle goes through its own cycle of growth and shedding, which is not tied to the calendar. This complex internal mechanism is influenced by entirely different things.
Main reasons for changes in hair growth rate:
- Genetic predisposition and innate characteristics of follicles;
- Diet quality, especially blood iron levels;
- Stress levels and the presence of inflammatory processes;
- Hormonal shifts, such as thyroid disorders or hormone surges after childbirth;
- Use of specific medications, serious illnesses, surgeries, or rapid weight loss.
Any of these factors can cause hair loss. That is why the consequences of severe stress or illness are only noticed on the hairbrush several months later.
In the end, it turns out that summer is a wonderful time, but you shouldn’t expect miracles for your hair. Instead of relying on the sun, it is far more beneficial to maintain a balanced diet and overall health, because it is internal balance that keeps hair strong all year round.
