Hair-growth patterns vary less from person to person than you might think. Understanding the growth cycle can help you predict the rate at which your own hair will grow.
You probably know people whose hair seems to grow overnight, going from short locks to a luscious, flowing mane in a matter of months. Meanwhile, growing out your post-breakup pixie cut seems to take forever.
Although it's true that there's some variation in the rate at which hair grows, this difference isn't nearly as pronounced as you might think. Understanding the hair growth cycle can help you manage your own hair's growth.
Understanding the Hair Growth Cycle
All hair follows a natural growth cycle. While it might look like all your hair is growing simultaneously, some hairs are growing while others are resting. There are three stages of the hair growth cycle.
Anagen phase: This growth phase lasts three to five years, producing an average hair length of 18 to 30 inches. There's significant variability in hair growth, though, with some people having much longer or shorter anagen phases.
Catagen phase: This is a short period of about 10 days during which your hair stops growing.
Telogen phase: This is a resting period that begins with your hair falling out. The follicle usually remains inactive for about three months and then produces a new hair shaft.
Hair follicles are never all in the same cycle, which explains why you don't go bald during the telogen phase. However, different disruptors can produce baldness by causing too many hairs to go into the telogen phase at once. Hormonal changes, health issues, and genetics all figure prominently in disruption of the hair-growth cycle.
Most people lose 80 to 100 hairs per day. If you notice significantly more hair loss than this, it could signal a problem with your hair's growth cycle or your health.
How Fast Does Hair Normally Grow?
Most people's hair grows about a half inch a month, with variations of a quarter inch to half inch in either direction. Of course, a number of factors can make hair growth appear faster or slower.
Very dry, damaged hair may break off during the growth cycle, creating the illusion that hair isn't growing at all. Healthy hair remains lustrous and thick throughout the growth cycle, potentially creating the illusion that you have more hair than you really do.
Variations in Hair Growth
In addition to health-related disruptions—such as starvation diets—a number of lifestyle and environmental factors can alter your hair's growth cycle. Some examples include:
• Climate changes. Hair tends to grow more quickly during hot, humid summers.
• Pregnancy and childbirth. Fewer hair follicles enter the telogen phase during pregnancy. But after giving birth, many more hairs enter this phase, potentially leading to increased hair loss.
• Medications. Drugs that act on the endocrine system disrupt hormones. Other medications can also alter hair-growth patterns.
• Damage to hair follicles. Scalp infections, severe burns, or repeatedly pulling out individual hairs can impede or stop hair growth.