Sometimes, it seems like everything we love to do to our tresses — like dying them in this season’s dreamy pastel hues, going smooth and sleek, or pumping up the volume — is a one-way ticket to breakage city. Luckily, there are plenty of hacks to repair your hair and boost healthy growth. But if your strands change texture overnight, or your ends start splitting for no clear reason, an underlying health issue might be responsible.

A woman smiles as her hair blows in the wind

Thyroid Problems

Temporary hair loss can be a sign that your thyroid gland is overactive (hyperthyroidism) or underactive (hypothyroidism). That’s because thyroid disease can cause something called telogen effluvium, which sounds like an awesome Swedish nightclub but actually has to do with your hair cycle.

“The growth phase of an individual scalp hair (anagen) is about three years, after which it takes three weeks to get prepared to fall out (catagen) and three months to fall out (telogen),” explains board-certified dermatologist and University of Southern California clinical instructor of dermatology Tsippora Shainhouse. Most of the time, around 85 percent of your strands are in that growth phase — but with telogen effluvium, an above-average proportion of your hair gets stuck in their rest phase.

Additionally, hypothyroidism can dry out your hair, leaving it less shiny and more prone to breakage; hyperthyroidism can lead to greasier tresses, but also seems to up your chances of breakage. Basically, if there’s any drastic, unexplained change in your hair’s condition, it’s worth visiting your doctor to see if your thyroid’s at fault.

Stress

Yes, your mental health can totally affect your hair. Dr. Shainhouse notes that good ol’ telogen effluvium can strike after your body goes through physical *or* emotional strain. “When the body is stressed, it can shift up to 50 percent of the scalp hairs into the catagen phase,” she explains. “Three months later, you will suddenly notice that your hair looks less dense/full.” If stress can cause such a dramatic change in your hair, just think how it must be affecting the rest of your body — and your mood.

The good news: Dr. Shainhouse says that for most people, hair begins to grow back after about six months. “If you are otherwise healthy, then treatment is mostly a watch and wait game,” she tells us. However, she cautions, “For some women, this hair loss unmasks an underlying female-pattern hair loss, and the hair may never look as thick as it once did.” If that’s the case for you, try not to let your hair become a new source of stress. Practice self-care (or check in with the pros!) to target any ongoing mental health issues.

A woman smiles with her hand in her hair

Dietary Factors

You know that old expression, “You are what you eat”? Turns out, it also applies to your hair. If something’s limiting your dietary options — like an undiagnosed food allergy or GI condition — it might show in your hair. Dr. Shainhouse points out that telogen effluvium can occur in response to the dietary restrictions themselves (for example, if you’re taking in fewer calories and less protein, or if you’re only able to consume liquids) and their consequences (especially rapid weight loss).

To restore your strands to their former glory, Dr. Shainhouse advises, “Develop a healthy eating schedule that includes food-derived vitamins and nutrients, and ensure that you are getting enough protein.”

Androgenic Alopecia

“This is a female version of male pattern baldness,” shares Dr. Shainhouse. “Women maintain their hairline but notice a widened center part and thinning at the crown.” This hair loss can start as early as your late teens, although it’s more common in women from their mid-30s onward. That’s because hormones play a significant role: “When estrogen levels dip in the perimenopausal period, the testosterone effect presents as hair thinning.”

If you do experience androgenic alopecia earlier on, it could actually be a symptom of something else. “Some women have a condition called polycystic ovarian syndrome (PCOS), in which they make so much estrogen that some gets converted to testosterone, which can contribute to loss of hair,” Dr. Shainhouse says. If this is the cause of your hair loss, then treatment for PCOS may also help with the androgenic alopecia.

However, Dr. Shainhouse reminds us that it’s difficult to regrow or thicken hair after it has been affected. “Supplements like biotin, silica, and horsetail can help thicken existing hairs,” she says. Other treatment options might include dandruff shampoo, hair transplantation, or red light therapy or topical agents like Rogaine to increase scalp circulation.

A worried-looking woman touches her hair

Traction Alopecia

Time under tension is great for strengthening your muscles, but it’s not so good for your hair follicles. Stressful styling can lead to traction alopecia, a potentially permanent type of hair loss. Dr. Shainhouse explains that, by pulling at your roots, styling practices like frequent brushing and wearing tight braids or buns can cause follicular degeneration syndrome. “With tight hair styling, the hairs get pulled; the follicles get traumatized,” she explains.

And it’s easier to overdo it than you might think. “If your scalp hurts from your styling, then your hair is being pulled too tight,” says Dr. Shainhouse. “That feeling of scalp tenderness after taking out your ponytail at the end of the day means that your hair has been pulled too tight.” But if that sounds familiar, don’t panic. Dr. Shainhouse says that as long as this is an occasional occurrence, the hair will grow back.

“With persistent tension and trauma to the follicles, the follicle can be destroyed,” Dr. Shainhouse warns, however. “Fibrous scar tissue can develop around and within the old hair follicle. Hair cannot grow back.” She offers the following tips to prevent stressing your follicles:

1. Let your hair down. “Wear looser hairstyles,” the doctor suggests. “Buns and ponytails are okay, so long as you give your hair a break once in a while. Don’t wear them every day. Your scalp should not hurt when you take them out.”

2. Be gentle. “Avoid pulling your hair too hard while styling,” recommends Dr. Shainhouse. “Don’t tug with round brushes while straightening.” She also advises being careful with back teasing, which can cause major damage to your tresses.

3. Lighten up. “Hair extensions are heavy,” Dr. Shainhouse points out. “The tension and traction from the extension can traumatize the follicle and lead to scarring and more hair loss. Be very careful, and consider using clip-in extensions for short periods only.”

Has your hair clued you in to any big health issues? Tell us about it @BritandCo!

(Photos via Getty)