An increase in shedding is more likely to occur in late summer and early autumn. This temporary increase in fallen strands results from the hair follicle’s natural biological cycle and damaging external factors associated with the summer season. This phenomenon is known as seasonal shedding, which is different from persistent hair loss. Understanding this distinction can help manage the excess hair found in the shower drain.
The Biological Mechanism of Seasonal Shedding
The hair on the scalp cycles through three main phases: anagen (growth), catagen (transition), and telogen (resting/shedding). While approximately 80 to 90 percent of hair follicles are in the long anagen phase at any given time, a small percentage are always in the telogen phase, preparing to shed. Seasonal shedding occurs because a greater number of follicles are synchronized to enter the resting phase simultaneously.
A prominent theory, supported by some studies, suggests that a maximal proportion of follicles enter the telogen phase during the summer months, specifically around July. Since the telogen phase lasts for about 100 days before the hair is released, this peak resting period in summer results in the noticeable increase in shedding approximately three to four months later, during the late summer and early autumn. This timing may be an evolutionary trait, inherited from mammals who grow thicker coats for winter and shed them in warmer months, or grow more hair in summer to protect the scalp from intense sunlight.
Environmental Factors That Exacerbate Shedding
External summer conditions compound the problem by weakening the hair shaft, making it prone to breakage or premature release. High exposure to ultraviolet (UV) radiation is a major culprit. Both UVA and UVB rays penetrate the outer layer of the hair shaft, damaging its protein structure. UVB radiation is particularly responsible for the loss of hair protein, which leads to weakened and brittle strands.
Increased humidity and excessive sweating on the scalp can also disrupt follicle health. The accumulation of sweat, oil, and dirt may clog the hair follicles, potentially impeding healthy growth. Furthermore, swimming in pools or the ocean exposes hair to chlorine and salt water, which strip away natural oils and moisture, making the shaft dry and susceptible to breakage.
Identifying When Shedding Becomes Hair Loss
A typical, healthy scalp normally sheds between 50 and 100 hairs daily. Seasonal shedding is a temporary increase above this baseline, often lasting for a finite period of four to eight weeks. Hair density should return to normal without intervention.
If the increased shedding persists for longer than two months, or if it is accompanied by visible signs of thinning, it may indicate a form of hair loss that requires professional attention. Warning signs include a widening part, patchy loss, or a lack of regrowth where hair has fallen out. When excessive shedding, known as telogen effluvium, becomes prolonged or severe, consulting a dermatologist or trichologist is the appropriate next step to rule out underlying medical causes like hormonal imbalances or nutritional deficiencies.
Essential Summer Hair Care Strategies
Protecting the hair from intense summer elements mitigates seasonal stress and supports the hair cycle. Shielding the hair from UV radiation involves wearing a wide-brimmed hat when outdoors for extended periods. Applying leave-in conditioners that contain UV filters can also help create a protective barrier against sun damage.
When swimming, wet the hair with fresh water before entering a chlorinated pool or saltwater ocean to minimize the absorption of damaging chemicals and salt. Immediately after swimming, follow a thorough rinse with fresh water with a gentle, sulfate-free shampoo to remove any remaining residue. Handling wet hair gently, avoiding tight hairstyles, and minimizing the use of heat styling tools will help prevent heat-induced damage and breakage during this vulnerable period.