Can thyroid problems cause snoring? Hypothyroidism, goiter and sleep apnea

Thyroid problems can play a part in snoring and sleep apnea, mainly in two ways. An underactive thyroid (hypothyroidism) can make the tongue and tissues around the airway swell, and a large goiter can press on the windpipe. The good news is that both are treatable, and treatment sometimes improves breathing at night too.

The research is smaller and messier than for weight or alcohol, so this article sticks to what the studies actually show.

Can thyroid problems cause snoring and sleep apnea?

Thyroid problems can contribute to snoring and obstructive sleep apnea, especially an untreated underactive thyroid. The NHLBI lists low thyroid hormone levels among the hormone problems that raise the risk of obstructive sleep apnea, and explains that hormone levels can affect the size and shape of the face, tongue and upper airway.

That fits with what doctors see in the throat. In a 2006 study from New Delhi, researchers checked 50 people with newly diagnosed, untreated hypothyroidism. They looked for signs that crowd the upper airway, such as an enlarged tongue (macroglossia), puffiness of the face and a kind of muscle swelling called myoedema. Those signs became much less common after thyroid hormone treatment, which suggests the airway itself changes when thyroid levels are low.

Weight is the other piece. The NIDDK lists weight gain as a common symptom of hypothyroidism, and extra weight around the neck is one of the best-known causes of snoring. Our guide to weight loss and snoring covers that link in detail.

How common is sleep apnea in people with hypothyroidism?

Sleep apnea is fairly common in people with untreated hypothyroidism, though estimates vary a lot between studies. In the 2006 study above, 15 of the 50 patients (30%) had sleep-disordered breathing, defined as an AHI of 5 or more. In an older 1984 study of 11 people with new hypothyroidism, 9 had apnea episodes.

Those are small groups, and both looked at people at the point of diagnosis, when thyroid levels were at their lowest. They don't tell you how many people with well-controlled thyroid disease have sleep apnea.

Hypothyroidism itself is common. The NIDDK says nearly 5 out of 100 Americans aged 12 and older have it, although most cases are mild or have few obvious symptoms. It's much more common in women and in people over 60.

What do the larger reviews say?

The larger reviews disagree, which is why we rate this evidence as limited. A 2016 meta-analysis pooled 12 studies and 5 case reports, comparing 192 people with sleep apnea and hypothyroidism against 1,423 with sleep apnea and normal thyroid function. The hypothyroid group had a higher AHI, more time with oxygen below 90% and more daytime sleepiness at diagnosis. The authors noted that obesity could be a confounder, since body weight tracked with AHI.

A 2023 meta-analysis of 23 studies came to a different conclusion. It found that thyroid hormone levels in people with sleep apnea were no different from those in healthy controls, and that TSH, free T3 and free T4 did not correlate with AHI. It estimated that 6% of people with sleep apnea had hypothyroidism and 8% had subclinical hypothyroidism. The authors called the relationship "controversial" and asked for better research.

Put together, the most reasonable reading is this. Most people with sleep apnea don't have a thyroid problem. But in someone with an untreated underactive thyroid, low thyroid hormone can make the airway more crowded and sleep apnea more likely or more severe.

What are the symptoms of an underactive thyroid?

An underactive thyroid causes symptoms that build slowly, which is why it's easy to miss. The NIDDK lists fatigue, weight gain, trouble tolerating cold, joint and muscle pain, dry skin or thinning hair, heavy or irregular periods, a slowed heart rate and depression as common symptoms.

The NIDDK adds that because hypothyroidism develops slowly, you may not notice symptoms for months or even years. It also points out that fatigue and weight gain are common and don't necessarily mean you have a thyroid problem.

Here's the tricky part for anyone who snores. The NHS says sleep apnoea can also leave you feeling very tired during the day, with trouble concentrating and mood swings. If you've been told you snore loudly, stop breathing or gasp at night, and you also feel run down and cold all the time, it's worth asking about both. Our list of sleep apnea warning signs covers the night-time symptoms.

Can a goiter cause snoring or sleep apnea?

A goiter, or enlarged thyroid, can contribute to breathing problems at night if it's large enough to crowd the airway. Cleveland Clinic says a goiter doesn't usually cause serious problems, but a large one can make it hard to breathe, swallow or talk.

Cleveland Clinic lists difficulty swallowing, coughing and a hoarse voice among possible goiter symptoms. It says iodine deficiency is the most common cause, and that a goiter can occur in a thyroid making too much hormone, too little hormone or a normal amount.

How much a goiter adds to sleep apnea is still unclear. A 2022 meta-analysis pooled six cohort studies with 221 people who had sleep apnea and then had thyroid surgery. After surgery, AHI fell by about 6.4 events per hour on average. That's a real but modest drop. The surgery wasn't linked to a significant change in how many people could stop using CPAP, and daytime sleepiness scores didn't improve significantly. The authors concluded that thyroid surgery is associated with limited improvement in sleep study measures.

Results for any one person can differ from the average, so if you have a large goiter, it's worth mentioning to a sleep doctor alongside your other symptoms.

How do doctors check for a thyroid link?

Doctors check for a thyroid link with a blood test, usually alongside a sleep evaluation. The NHLBI says that when someone is being assessed for sleep apnea, a provider may order blood tests to check thyroid hormone levels, because low thyroid hormone is one of the conditions that can cause sleep apnea.

Cleveland Clinic says goiter testing can include a thyroid blood test that measures thyroid-stimulating hormone (TSH), an antibody test, a thyroid ultrasound to check size and nodules, and a biopsy if a nodule needs checking. The NIDDK notes that a hypothyroidism diagnosis can't be based on symptoms alone, which is why blood tests matter.

On the sleep side, the test is a sleep study. Our guides to the home sleep apnea test and what happens at a sleep study explain both options. If you're preparing for an appointment, our list of questions to ask your doctor about snoring includes asking about thyroid tests.

Does treating hypothyroidism improve snoring and sleep apnea?

Treating hypothyroidism can improve sleep apnea in some people, and the early studies are encouraging. In the 1984 study, average apnea frequency fell from about 72 to about 13 events per hour after 3 to 12 months of thyroxine replacement, and body weight didn't change. The patients also woke up far less often during the night.

The 2006 study found similar results. Sleep-disordered breathing went away in 10 of the 12 patients who had a repeat sleep study after their thyroid levels were corrected. Signs of airway crowding, like facial puffiness and tongue swelling, became much less common at the same time.

There are two cautions. Both studies are small, and both looked at people with newly diagnosed, untreated disease. Many people with sleep apnea and thyroid disease will still have sleep apnea after their thyroid is controlled, especially if weight, jaw shape or other factors are involved. That's why a repeat sleep test, rather than how you feel, is the way to find out whether your breathing has really changed.

The NIDDK says hypothyroidism is treated with levothyroxine, a thyroid hormone medicine identical to the one a healthy thyroid makes. Doctors usually recheck blood levels 6 to 8 weeks after starting it and adjust the dose. The NIDDK is clear that you should never stop taking it without talking to your doctor first.

Should you wait for your thyroid to settle before treating sleep apnea?

You shouldn't put sleep apnea treatment on hold without talking it through with your doctor. If a sleep study shows moderate or severe sleep apnea, it's worth remembering that thyroid treatment took 3 to 12 months to show its full effect in the 1984 study, and the NHLBI says sleep apnea may raise the risk of high blood pressure, heart disease and stroke.

A common approach is to treat both at once and then retest. If your thyroid treatment brings your AHI down, your sleep doctor can decide whether you still need CPAP or another treatment. Our overview of sleep apnea treatment options and whether sleep apnea can go away covers what that conversation might look like.

When should you see a doctor?

You should see a doctor if your snoring comes with breathing pauses, choking or gasping, heavy daytime sleepiness, or any swelling or lump in your neck. Neck swelling with hoarseness or trouble swallowing deserves a prompt visit on its own, whether or not you snore.

It's also worth asking for a thyroid check if your snoring started or got louder at the same time as other changes, like weight gain you can't explain, feeling cold, dry skin or new tiredness. Our article on why you might start snoring suddenly covers other causes of new snoring.

This article is general information, not medical advice. Your doctor can tell you whether your thyroid could be part of the picture.

Read next

• Snoring vs sleep apnea: how to tell the difference
• Sleep apnea in women
• What is AHI?

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.