Testosterone and sleep apnea: can TRT make it worse, and does sleep apnea lower testosterone?

Testosterone and sleep apnea are linked in both directions. Testosterone therapy can make sleep apnea a little worse, at least in the first weeks, and men with sleep apnea tend to have lower testosterone. Neither link is huge, and treated sleep apnea doesn't automatically rule out testosterone therapy. But it's a pairing that deserves a careful conversation with your doctor.

This article covers what the guidelines say, what the trials found, and the questions worth asking before and during treatment.

Can testosterone therapy make sleep apnea worse?

Testosterone therapy can make sleep apnea worse in some men, though the effect in studies is modest and may be temporary. The clearest evidence comes from an 18-week randomized trial in Australia that gave 67 obese men with severe sleep apnea either testosterone injections or a placebo, alongside a weight-loss diet.

At 7 weeks, the men on testosterone had a worse oxygen desaturation index, by about 10 events per hour, and spent more of the night with oxygen below 90%. By 18 weeks, those differences were no longer statistically significant. The researchers concluded that testosterone mildly worsens sleep-disordered breathing in a time-limited way. The effect didn't depend on how low the men's testosterone was to begin with.

A 2021 review of the research found the same pattern across the decades. Early case reports, starting in 1978, described worse breathing pauses on testosterone, while some later studies found no increase. The reviewers concluded that testosterone therapy likely plays a small, possibly time-limited role in worsening or bringing on sleep apnea, and that doctors may choose to be cautious in men with severe sleep apnea.

The reviewers also said older theories, such as testosterone narrowing the airway by building tissue, have largely been disproven. The more likely explanation is that testosterone changes how the brain responds to low oxygen.

Does testosterone therapy raise the risk of a sleep apnea diagnosis?

Testosterone therapy was linked to a higher risk of being diagnosed with sleep apnea in one large study. Researchers followed 3,422 US military service members, retirees and dependents aged 40 to 64 who were prescribed testosterone between 2006 and 2010, and compared them with matched men who weren't.

The 2-year risk of a sleep apnea diagnosis was 16.5% in the testosterone group and 12.7% in the comparison group. The authors called the higher risk noteworthy. The same study found no rise in blood clots and a lower rate of heart events in the testosterone group, so it isn't a story of testosterone being dangerous across the board.

Keep in mind what a study like this can and can't show. Men on testosterone see doctors more, and their doctors may be more alert to sleep apnea, so some of the difference could come from more testing rather than more disease. That's part of why the overall evidence is rated moderate rather than strong.

What do the guidelines say about testosterone and sleep apnea?

The main guideline says not to start testosterone in men with untreated severe sleep apnea. The Endocrine Society's 2018 clinical practice guideline recommends against starting testosterone therapy in men who have untreated severe obstructive sleep apnea, listing it alongside other conditions such as uncontrolled heart failure and elevated hematocrit.

Notice the wording. The caution is about untreated and severe sleep apnea. It doesn't say men with mild sleep apnea, or men whose sleep apnea is treated, can never use testosterone. That's a judgement your doctor makes with you.

The same guideline sets a high bar for diagnosing low testosterone in the first place. It recommends diagnosing hypogonadism only in men with symptoms and signs of testosterone deficiency and with clearly and consistently low levels, measured on a fasting morning blood test and confirmed with a repeat test. It also recommends monitoring testosterone and hematocrit levels during treatment.

MedlinePlus makes the practical point for patients. Before starting testosterone injections, it says to tell your doctor if you have or have ever had sleep apnea.

Does sleep apnea lower testosterone?

Men with sleep apnea tend to have lower testosterone than men without it, though it's not clear which causes which. A 2023 meta-analysis of 24 case-control studies found that testosterone levels were significantly lower in men with sleep apnea than in controls. There was no difference in women.

The results varied a lot between studies. The authors found that race, age, body mass index and the lab method used explained much of the variation. Weight is the obvious overlap. The NHLBI lists obesity as a risk factor for obstructive sleep apnea, and body mass index was one of the factors that explained differences between studies, so the two conditions may share a cause rather than one driving the other.

The NHLBI also says sleep apnea is more common in men than women, and that men are more likely to have serious sleep apnea and to be diagnosed younger. If you're being tested for low testosterone, it's worth mentioning any snoring or daytime sleepiness too, since the two conditions often turn up together. Our guide to sleep apnea and erectile dysfunction covers a related overlap.

Will treating sleep apnea raise testosterone?

Treating sleep apnea with CPAP doesn't appear to raise testosterone by itself. A 2019 meta-analysis pooled 10 cohort studies and 2 randomized trials with 388 patients. CPAP use was not linked to a significant change in total testosterone or in other related hormones, and the result held for men who were low to begin with.

The authors concluded that the evidence doesn't support a direct link between sleep apnea and testosterone, and suggested strategies other than CPAP for managing low testosterone in men with sleep apnea.

That doesn't make CPAP less worthwhile. It treats the breathing pauses, oxygen drops and daytime sleepiness that sleep apnea causes, which is the point of treatment. Just don't expect it to fix a low testosterone result. Our guides to sleep apnea treatment options and getting used to CPAP cover the practical side.

Why do doctors check red blood cells on testosterone?

Doctors check red blood cells, usually as hematocrit, because testosterone can raise them, and the Endocrine Society recommends monitoring hematocrit during treatment. Sleep apnea may add to that rise. A 2020 study reviewed 474 men treated for low testosterone by one provider and found that 13.1% developed a hematocrit of 52% or higher.

Men with sleep apnea were about twice as likely to develop a high hematocrit, even after adjusting for age and body mass index. Among the men who had both, more than half were noted to use their CPAP poorly. The study was retrospective and from a single clinic, so the authors called for more research, but they advised doctors to strongly consider sleep apnea in men on testosterone who develop a high red blood cell count.

What should you ask before starting testosterone?

The most useful question to ask before starting testosterone is whether you should be checked for sleep apnea first. That's especially true if you snore loudly, someone has seen you stop breathing or gasp, or you're very sleepy in the day. Our list of sleep apnea warning signs and the STOP-BANG questionnaire can help you decide whether to raise it.

Other questions worth asking:

• Has my low testosterone been confirmed with two fasting morning tests?
• Could weight, sleep apnea or another condition be lowering my levels?
• If I have sleep apnea, is it treated well enough to start?
• How will we monitor my breathing, hematocrit and symptoms once I start?
• What signs should make me call you?

If you already use CPAP, keep using it every night once you start testosterone, and keep an eye on your machine's event count. If it climbs, or you feel sleepier, tell your doctor rather than stopping either treatment on your own. Our article on what AHI means explains how to read that number.

What about women and testosterone?

Most testosterone and sleep apnea research has been done in men, so there's little to say with confidence about women. The 2023 meta-analysis found no difference in testosterone levels between women with and without sleep apnea. The NHLBI does list hormone problems in polycystic ovary syndrome (PCOS) as a sleep apnea risk factor, and our guide to sleep apnea in women covers that and other risks.

When should you see a doctor?

You should see a doctor if you have signs of sleep apnea, whether or not you're thinking about testosterone. Loud snoring with pauses, choking or gasping, and heavy daytime sleepiness all deserve a proper look, and a home sleep apnea test is often the first step.

If you're already on testosterone and your snoring gets worse, your partner notices more pauses or you feel more tired, tell the doctor who prescribes it. Don't stop testosterone or change your dose on your own.

This article is general information, not medical advice. Your doctor can help you weigh the benefits and risks of testosterone therapy for your situation.

Read next

• Snoring vs sleep apnea
• Sleep apnea effects on the body
• Can sleep apnea go away?

* 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.