The Science Behind Hair Growth & Why You Need Frequent Trims

You’ve probably been told by your favorite stylist that you should have your hair trimmed once every four to eight weeks depending on how fast it grows. If you’re trying to grow out your locks, this may seem counterintuitive. Here, you’ll learn more about the hair growth process and why you should trim your hair often.

Hair Growth: The Science

Hair is basically dead cells made of keratin (and other bits) that grows from a root in the bottom of each hair follicle on your scalp. As the blood vessels in your scalp continue to supply the root with the nutrients, the protein in the root will grab up the keratin, the collagen, the biotin, and the various other goodies it needs to create a strand of hair.

It is also important to keep in mind that your hair grows a total of about six inches each year. Though most mammals experience seasonal hair growth (think of how cats and dogs fill out with a “winter coat” and then shed every spring, leaving their hair everywhere), human growth cycles are random and sporadic and occur in three phases:

• Anagen – This is the active phase of hair growth. During the anagen phase, you’ll gain about a centimeter each month. If your hair doesn’t grow past a certain length, that’s probably because you have a short anagen phase. Pretty neat, right? If your hair seems to grow very long very easily, then you probably have an extra-long anagen phase. Depending on your unique biology, this phase can last from two to six years.
• Catagen – This is a transitional period, and right now as you read this, about 3% of the hair on your head is in the catagen phase. Growth stops and club hairs – hairs that have a bulging end down inside the follicle – are formed.
• Telogen – This is the “rest” phase for your hair during which nothing much happens at all. Right now, between 5% and 10% of the hairs on your head are in the resting phase, which lasts for at least 100 days. When you shed a hair and notice a bulb at the end, this is indicative of the telogen phase. Fun fact: it’s perfectly normal to lose 25 to 100 telogen hairs naturally every single day when brushing your hair or simply moving your head.

Why You Need Trims

Trims do not really make your hair grow faster regardless of what you’ve heard. In fact, trims are designed to shear off the oldest part of the hair shaft before it becomes dry and brittle, which is when it is most likely to split. That split can run up the length of the shaft and effectively ruin most of the entire hair, too, which can cause everything from frizz to breakage. This means that even though trims won’t make your hair grow faster, they’ll keep your existing hair much healthier – and that’s what appears to make it grow faster.

If you’re struggling to grow your hair out, there are things you can do to help. Regular scalp massages and the use of good-quality products will go a long way. This can help stimulate the anagen phase to last a little longer and ensure your strands get the nutrients they need. Trimming your hair regularly is also important for growing out your hair as it ensures your tresses stay healthy throughout the process.