Sun & Hair Growth Rate

Summer hair and sunshine — Photo: Zapylaiev Kostiantyn/Shutterstock

Q: Does the sun make your hair grow faster? Is spending a lot of time outside in the sun good or bad for hair growth?

A: Contrary to what some people might hope, spending time in the sunshine has absolutely no effect on how fast your hair grows. Your hair follicles operate on their own biological timeline, following a natural growth cycle that's determined primarily by genetics, hormones, nutrition, and overall health. Unlike plants that use photosynthesis to convert sunlight into energy for growth, human hair doesn't have the ability to harness solar energy to speed up its development.

Hair growth occurs beneath the surface of your scalp, where hair follicles produce new cells that push upward to form the hair shaft. This process happens at a relatively consistent rate of about half an inch or 1.25 cm per month for most people, regardless of how much time you spend outdoors.

However, sun exposure does have significant effects on your existing hair and scalp health, and these effects are predominantly negative. The sun's ultraviolet rays can cause considerable damage to both your hair and the sensitive skin on your scalp. UV radiation breaks down the proteins in your hair shaft, particularly keratin, which is the primary structural component that gives hair its strength and elasticity. This protein breakdown leads to hair becoming brittle, dry, and more prone to breakage.

One of the most noticeable effects of prolonged sun exposure is the gradual bleaching of your hair's natural pigments. While this might create subtle highlights that some people find attractive, this lightening process is actually a sign of damage occurring at the molecular level. The UV rays break down melanin, the pigment that gives your hair its color, and this process is irreversible.

The scalp itself is particularly vulnerable to sun damage because it's often forgotten when people apply sunscreen. Severe sunburn on the scalp can actually damage the hair follicles themselves. When follicles are damaged by intense UV exposure, they may go into a resting phase or shut down completely, resulting in thinning hair or bald patches in the burned areas.

Woman wearing a straw hat to protect her hair from the sun

People with certain hair types face even greater risks from sun exposure. Those with fine hair have less natural protection since their individual hair strands are thinner and more delicate. Similarly, people with naturally light-colored hair, including blonds and redheads, tend to have less melanin in both their hair and scalp skin, making them more susceptible to UV damage.

The cumulative effects of sun damage on hair include increased porosity, which means your hair loses its ability to retain moisture. This leads to dryness, frizz, and hair that feels rough or straw-like to the touch. Sun-damaged hair also tends to tangle more easily and may appear dull or lackluster because the damaged cuticle layer can't reflect light properly.

Thus, while the sun won't make your hair grow any faster, it can certainly make your existing hair less healthy and less attractive over time. Taking proactive steps to protect your hair and scalp from UV damage will help ensure that your hair remains strong, shiny, and beautiful regardless of how much time you spend enjoying the great outdoors.

©Hairfinder.com

See also:

How hair responds to sun exposure

Is there something like sun block for hair?

Does the tanning bed hurt your hair in any way?