Dermatologist explained: What causes seasonal hair loss?

According to Farrant, environmental factors, especially temperature changes, can affect the hair growth cycle: “Hair loss can become more noticeable during the colder months. This is known as ‘seasonal hair loss,’ which usually occurs around September.”

HAIR CYCLE

The hair growth process consists of four phases: anagen (growth), catagen (transition), telogen (resting), and exogenous (shedding). Farrant explains, "Each hair follicle operates on its own timetable. The hair follicle entering the resting phase shrinks, and eventually, the old hair falls out to make room for the new hair." Experts note that in seasonal hair loss, some of these cycles synchronize, making the shedding more noticeable for a while.

Vitamin D and Seasonal Effects

This may be linked to increased vitamin D levels during the summer months, Farrant says. “Increased exposure to sunlight may affect the hair follicle cycle. When temperatures drop, more hairs enter the exogenous phase.” The good news is that this shedding usually lasts about three months and doesn’t lead to permanent hair loss. WHEN SHOULD YOU BE CONCERNED? Seasonal hair loss is usually mild, but in some cases, it can be a sign of underlying health problems, Farrant says. “If you’re losing hair in patches, developing noticeable patches of baldness, or have a family history of hair loss, conditions like hereditary baldness, psoriasis, or thyroid problems should be investigated.”

NUTRITION FOR HEALTHY HAIR

Since most of the hair strands are made up of protein, the expert recommends a balanced and protein-rich diet.

Foods rich in iron, zinc, folate, and omega-3s can support hair growth. “Eating fresh foods, paying attention to sleep patterns, and managing stress are anti-inflammatory lifestyle habits that can reduce hair loss,” Farrant says.

She notes that hair should be washed more frequently in the summer due to increased sweating, but that over-washing in the winter can dry out the scalp and increase hair loss: “The scalp becomes drier in the winter. Over-shampooing can disrupt the hair’s natural oil balance and lead to itchy, inflamed skin.”