It’s shaped like a butterfly, but the thyroid gland can sting like a bee if its hormone production goes awry.

The thyroid produces hormones essential for metabolism and brain activity. If you notice any of the following signs persisting, or have more than one, endocrinologists recommend a simple blood test to gauge your hormone levels.

1. Sleep changes
If you’ve always been a good sleeper but suddenly can’t snooze through the night, it could signal a thyroid problem. An overactive thyroid pumps out certain hormones (triiodothyronine, known as T3, and thyroxine, known as T4) in excess, which can overstimulate the central nervous system and lead to insomnia, says Dr Hossein Gharib, a Mayo Clinic endocrinologist. On the flip side, if you still feel tired after a full night’s sleep, or the need to sleep more than usual, you might have an underactive thyroid, in which case your body doesn’t produce enough of these hormones. Here are 13 more surprising things that could explain your sleep woes.

2. Out-of-nowhere anxiety?
Your thyroid might be hyperactive. Too many thyroid hormones can cause jittery feelings, says Dr Ashita Gupta, an endocrinologist at Mount Sinai Roosevelt Hospital, New York. “There’s more brain stimulation so it excites you to the point where you don’t feel good about it,” she says.

How many of these 15 sneaky things in your home that trigger anxiety could you easily do away with?

3. Changes in bowel habits
Frequent constipation could mean an underactive thyroid. Conversely, an overactive thyroid can create the need to go more frequently. Also, did you know you've been using the toilet wrong all this time?

4. Thinning hair
Thinning hair, particularly eyebrows, is a common sign of thyroid disease. An underactive or overactive thyroid throws off your hair growth cycle.

Here's how to cope with female hair loss.

5. Sweating at random times
Excessive sweating when you’re not exerting yourself is a common sign of a hyperactive thyroid. “The thyroid regulates the body’s energy production. Higher than normal hormone levels mean your metabolism is revved up, which causes people to feel overly warm,” says Gupta.

Here are 41 more strange symptoms that could signal a serious disease.

6. Clothes that fit tighter than usual?
An underactive thyroid might be to blame. “A lack of hormones decreases metabolism and calorie burning, so you may see gradual but unexplained weight gain,” says Gharib. Check out the most common weight-loss tips you should ignore.

7. Ravenous but losing – or not gaining – weight?
If you’ve made no major change to your diet or workout, you may have an increased metabolism from an overactive thyroid.

8. Brain fog
When your thyroid isn’t working right, neither is your brain. With an underactive thyroid, some people report feeling a brain fog, says Gupta. Others report subtle memory loss (the feeling it’s on the tip of my tongue!) or overall mental fatigue. An overactive thyroid can make it difficult to concentrate.

Here are some great ways to improve your memory, plus other health tips no what your stage in life.

9. Too much energy (like you’ve drunk five cups of coffee)
An overload of thyroid hormones speeds up your body processes, says Gupta. Patients say they feel like they’ve had too much caffeine or have heart palpitations even when they’re relaxed. Check out the 10 things that happen to your body when you quit coffee.

Overactive thyroid needs medication to slow the production and release of T4 and T3 hormones. If left untreated, surgical removal of some or all of the gland may be required. Underactive thyroid usually needs lifelong medication with levothyroxine, a synthetic thyroid hormone taken orally which restores hormone levels and helps reverse symptoms such as weight gain, fatigue, brain fog and constipation. Next, find out when medication can do more harm than good.

This article first appeared on Reader’s Digest.