Hair Growth Cycle: A Continuous Biological Rhythm

Healthy hair growth is governed by a natural cycle consisting of three distinct phases. Each strand on the scalp is at a different stage in this cycle, which explains why shedding a certain amount of hair every day is normal. Understanding this process is essential for recognizing changes in hair density, growth speed, and overall hair quality.

The anagen phase is the most important stage for determining hair length and density.

• Duration: Typically lasts 2 to 7 years, but in some individuals — due to genetics or optimal health — it can last even longer.
• Activity: Hair follicles are highly active, producing new cells that push the hair shaft upward.
• Growth Rate: Hair grows on average 1 cm per month, though this varies with age, nutrition, and hormonal balance.
• Significance:
  
  • A longer anagen phase allows the hair to grow very long.
  • A shortened anagen phase results in slower growth and difficulty achieving length.

Approximately 85–90% of scalp hairs are in the anagen phase at any given time.

The catagen phase is a brief but essential transitional period during which the hair prepares to detach from its blood supply.

• Duration: Around 2–3 weeks.
• Activity:
  
  • Cell division stops.
  • The follicle begins to shrink.
  • The hair (now called a “club hair”) separates from the dermal papilla — the structure that nourishes it.
• Significance:
  
  • Only 1–2% of hairs are in this stage.
  • It marks the controlled end of the growth period.

Although short, this phase ensures an orderly transition to the resting phase.

The telogen phase represents a period of rest before new growth begins.

• Duration: Typically 3–4 months, though stress or hormonal changes can extend it.
• Activity:
  
  • The hair remains anchored in the follicle but is no longer growing.
  • Eventually, the old hair is shed to make room for a new one.
• Significance:
  
  • Around 10–15% of scalp hairs are in telogen.
  • Shedding 50–150 hairs per day is considered normal.

A prolonged telogen phase can lead to excessive shedding — commonly seen in postpartum hair loss, stress-related shedding, or after illness.

Several internal and external factors can alter the duration of each phase, affecting hair growth, density, and resilience:

• Age: The anagen phase shortens with age, leading to slower growth and reduced hair thickness.
• Hormones: Thyroid disorders, pregnancy, menopause, and androgen levels greatly impact follicular activity.
• Stress: Physical or emotional stress can push many hairs prematurely into telogen, causing noticeable shedding (telogen effluvium).
• Nutrition: Deficiencies in iron, zinc, proteins, vitamins (B-complex, D), and essential fatty acids can disrupt the cycle.
• Medical Conditions & Medications: Some conditions suppress follicle activity or alter growth patterns.
• Seasonal Changes: Hair growth can fluctuate throughout the year, with increased shedding in late summer/early autumn.
• Lifestyle Factors: Poor sleep, smoking, restrictive diets, and chronic inflammation weaken the growth cycle.

A deep understanding of these phases allows XLhairspa to design treatments that:

• support the anagen phase for stronger, longer growth
• reduce premature shedding
• improve follicle vitality
• restore balance in disrupted hair cycles