If you’ve been feeling out of sorts—tired, depressed, or drastic weight changes—your thyroid could be the culprit. The thyroid, a butterfly-shaped gland located in your neck, is responsible for controlling a variety of bodily functions. When your thyroid isn’t working properly, it can affect everything from your mood to your periods to your bone health.

More commonly found in women, thyroid disorders affect nearly 30 million Americans—but many of those people are left untreated. Watch the video to find out more about your thyroid—including things that may be affecting it—so you can be better able to recognize symptoms and seek out the appropriate treatment if necessary. 

Don’t have time to watch? Read the full transcript:

1. It’s the engine of your body: The hormones it produces regulate your metabolism. Yes, that means how many calories you burn. But also: how fast your heart, brain, and other organs work.

2. Problems are more common in women: Perhaps because thyroid cells are sensitive to estrogen (the female sex hormone).

3. It can affect your fertility: Thyroid hormones influence your menstrual cycle. Out-of-whack thyroid hormones = out-of-whack periods. 

4. Giving birth can throw it off: 10% of women develop postpartum thyroid problems. Good news: Most cases resolve within 18 months. 

5. Signs of an underactive thyroid are: Fatigue, weight gain, constipation, dry skin, and depression. 

6. Signs of an overactive thyroid are: Irritability, weight loss, rapid heartbeat, thinning hair, bulging eyes, and shaky hands.