Thyroid and Sleep Apnoea: What New Research Suggests

Feeling tired no matter how long you sleep is one of the most common reasons people look into their health. New research from Brazil suggests that two conditions often behind that tiredness, an underactive thyroid and obstructive sleep apnoea, may be more closely connected than many people realise.

The study, from researchers at the Federal University of São Paulo, found that almost half of the people with hypothyroidism in their sample also had sleep apnoea. Here is what the researchers found, what it does and does not tell us, and what it might mean for you.

What the study found

Nearly half (49.5%) of participants with hypothyroidism also had obstructive sleep apnoea. Researchers analysed data from 761 adults in São Paulo taking part in a long-running sleep study. Each person had blood tests and an overnight sleep study in a laboratory, known as polysomnography, which is the most thorough way to measure sleep.

Around one in eight participants (12.6%) had hypothyroidism. The researchers had expected some overlap with sleep apnoea, as previous studies have typically reported figures of around 30 to 40%. The level they found was higher than that.

Compared with other participants, people with hypothyroidism tended to have more broken sleep and woke more often during the night. Higher levels of TSH, the hormone most commonly used to check thyroid function, were linked with a greater likelihood of more severe sleep apnoea.

The link also appeared to work in the other direction. Poorer sleep quality and more severe sleep apnoea were associated with a higher likelihood of hypothyroidism. The researchers say this points to a possible two-way relationship, with each condition potentially influencing the other.

A quick guide to both conditions

The thyroid is a small, butterfly-shaped gland in the front of your neck. It makes hormones that help regulate your metabolism, body temperature, heart rate and energy levels. When it does not make enough of these hormones, this is called hypothyroidism, or an underactive thyroid.

In the UK, the most common cause is an autoimmune condition called Hashimoto's thyroiditis, where the immune system attacks the thyroid. Symptoms tend to develop slowly and can include tiredness, weight gain, feeling cold, dry skin, hair thinning, constipation and difficulty concentrating. Because these symptoms are so common, an underactive thyroid can go unnoticed for some time.

Obstructive sleep apnoea happens when the airway repeatedly narrows or closes during sleep, briefly interrupting breathing. Each pause can cause a dip in oxygen levels and a brief awakening, often without the person knowing. Signs include loud snoring, pauses in breathing noticed by a partner, waking with a dry mouth or headache, and feeling sleepy during the day.

The overlap in symptoms is part of what makes this research interesting. Tiredness, low energy and poor concentration can feature in both conditions, so one may be overlooked when the other is being considered.

What about treatment?

Among participants with hypothyroidism, those taking thyroid hormone replacement slept around 49 minutes longer per night on average than those who were not. They also spent about 22 minutes more in deep sleep, the stage linked with physical recovery and memory.

The researchers were clear that treating an underactive thyroid does not replace the need to assess sleep apnoea separately. The two are distinct conditions, and both are associated with increased cardiovascular risk when left untreated. Anyone with symptoms of either should discuss them with their GP rather than assume one explains the other.

Keeping it in perspective

This is early-stage research, so it helps to be clear about what it can and cannot tell us. The findings were published as a conference abstract in the journal SLEEP rather than as a full research paper, which means the complete methods and data have not yet been set out in detail.

The study looked at people at a single point in time. It shows that the two conditions often occur together, but it cannot show that one causes the other, or which comes first. The researchers acknowledge this themselves.

The treatment comparison is also observational. People who were already receiving thyroid treatment were compared with those who were not, rather than being randomly assigned, so other differences between the groups may play a part. The group with hypothyroidism was also relatively small, at fewer than 100 people. The researchers plan further work to explore how the two conditions interact.

What this means for you

The main message from the researchers is that thyroid health and sleep are worth looking at together. If you have been told you have sleep apnoea, it may be worth asking your GP whether your thyroid function has been checked. If you have an underactive thyroid and still feel unrefreshed after sleep, or a partner has noticed snoring or pauses in your breathing, that is worth raising too.

You should speak to your GP if you have ongoing tiredness, loud snoring, breathing pauses during sleep, or daytime sleepiness that affects your work or driving. A blood test cannot diagnose sleep apnoea, which needs a sleep assessment arranged through your GP or a sleep clinic.

A thyroid blood test can be a useful starting point if you want to understand more about your energy levels. London Health Company's home finger-prick thyroid test measures key thyroid markers, including TSH, and is analysed in our own CQC-regulated laboratory in London. Every result is reviewed by our Medical Director before it is released, and we will advise you to see your GP if your results need follow-up.

Explore our thyroid blood test →

Reference

Xerfan EMS, Andersen ML, et al. Sleep Traits and Obstructive Sleep Apnea in Hypothyroidism: Findings from the EPISONO. SLEEP, 2026; 49 (Supplement 1): A463.

This article is for general information only and is not a substitute for medical advice. If you are worried about your symptoms, please speak to your GP.