It’s natural to lose strands of hair every day. Stress and certain health conditions may cause increased shedding.

Hair with plenty of volume, movement, and shine is what most people consider healthy. So when you look down at the drain and see a clump of lost hair strands, it’s easy to assume that there’s a health problem causing hair loss. But some hair loss is normal for everyone and at every age.

When you wash your hair thoroughly in the shower, hairs that are already loose or disconnected from your scalp congregate near the drain. While it might look like a lot, you’re probably seeing normal hair shedding.

If you’re experiencing hair loss that’s unusual for you, including bald spots, patchiness, and clumps of hair falling out, you should see your primary care physician or dermatologist.

According to the American Academy of Dermatologists, it’s normal to lose anywhere from 50 to 100 strands of hair per day. For people with longer hair strands, losing them may be more noticeable. Since there are 100,000 hair follicles — or more — on each person’s scalp, the loss of 100 or so hair strands a day doesn’t make a big difference in appearance.

Women tend to lose more hair strands per day than men. There’s no way to measure the difference objectively, because daily heat styling and frequent hair coloring plays a big part in how much of your hair sheds. Approximately 40 percent of women lose extra hair every day because of the way they style it. Women are also more likely than men to experience periods of increased hair shedding due to life events like pregnancy and menopause.

There are hundreds of thousands of hairs on your head, and every single one them is at a different stage of its two- to five-year lifespan. Hair grows and dies in phases, and nutrition, stress, hygiene, and daily styling all play a role in how much hair you lose daily.

The phase in which a hair strand is growing is called the “anagen” phase, and 90 percent of the hair strands you have are currently in that phase. Hair grows about 1 centimeter per month during the anagen phase. When something stops your hair from growing, it’s called anagen effluvium. Anagen effluvium is what you would typically think of when you think of “hair loss.”

The catagen phase comes next. Only about 1 to 2 percent of your hairs are in the catagen phase at any given time. This phase lasts two to three weeks. During the catagen phase, the hair strand stops growing.

The last phase of hair growth is the telogen phase. Hairs in the telogen phase are also called “club hairs.” During this phase, a hair strand will be at rest as it prepares to detach from your scalp. About 8 to 9 percent of your hair is in this phase at any given time.

Telogen effluvium describes having more than 10 percent of your hair in the telogen phase. Telogen effluvium is temporary, but more hair will fall out while you have it. Stress, surgery, or even having a fever for a few days can bring on telogen effluvium, but your hair will probably be back to normal within six months.

Some daily hair loss is normal. Increased hair loss can be a result of stress or a health condition. Other potential causes of hair loss include:

Excessive washing, bleaching, brushing, and heat styling can also have an impact on how much of your hair falls out every day. Once your hair follicle has been stretched or split as a result of a cosmetic hair treatment, the structure of the hair follicle is compromised.

You can perform a “pull test” on your hair at home. Start with a small area of clean, dry hair, and run your fingers through it, tugging gently once you get to the ends of your hair strands. If more than two or three hairs are left in your hand after each tug, you may be experiencing telogen or anagen effluvium. No more than 10 hairs per 100 strands being tugged should be coming out. You’ll need a doctor to determine the cause.

See your doctor if you’re concerned about how much hair you are losing every day. A gradual thinning on the top of your head, the appearance of patchy or bald spots on your scalp, and full-body hair loss are signs that there may be an underlying health condition. A doctor will be able to assess whether your hair loss is normal shedding.

It’s not unusual to lose hair strands every day. But if you’re worried about clumps of hair in your hairbrush or in the shower drain, talk to your doctor. Factors like stress, medication, and underlying medical conditions can all aggravate hair loss. A professional assessment can put your mind at ease.