Before you blame low testosterone, get screened for sleep apnoea

Obstructive sleep apnoea lowers testosterone, and it produces the exact symptom set men attribute to low testosterone: fatigue, low mood, poor concentration, reduced libido and weight gain. It is estimated to be undiagnosed in a large majority of affected adults. Treating apnoea can raise testosterone on its own, while testosterone therapy can worsen untreated apnoea. Order of operations matters here more than almost anywhere else in men's health.

By The Loaded Joint · Last updated 14 September 2026

A man in his thirties feels flat, sleeps badly, has put on weight around the middle, and has lost interest in things he used to want. He reads about low testosterone, and every symptom on the list matches. That list also matches obstructive sleep apnoea almost exactly, and one of these is far more commonly missed than the other.

Why the symptom lists overlap

Testosterone release is tied to sleep. The bulk of daily secretion happens during sleep, and it tracks the first few hours in particular, with the largest rise associated with the first episode of REM. Fragment sleep badly enough and you fragment the secretion.

Obstructive sleep apnoea fragments sleep by definition. Each apnoeic event ends in a brief arousal you never remember. A man with moderate apnoea can have hundreds of these a night and report that he sleeps eight hours.

So the causal arrow often runs apnoea to poor sleep to lower testosterone, not low testosterone to fatigue. Treat the sleep and the hormone frequently follows, without prescribing anything hormonal at all.

The part that makes the order of operations matter

Testosterone therapy can worsen untreated obstructive sleep apnoea. That is a recognised concern in clinical practice guidelines, which is why untreated severe apnoea is treated as a reason to hold off starting therapy rather than a footnote.

If you start testosterone without screening, and apnoea was the underlying problem, you have treated a downstream marker and potentially aggravated the upstream cause. You may also feel better initially, which makes the mistake hard to catch.

How to know whether this is you

The classic picture is snoring, witnessed breathing pauses, and daytime sleepiness. But plenty of people with apnoea do not snore loudly and do not fall asleep in meetings. Other signals worth taking seriously:

• Waking unrefreshed regardless of duration
• Morning headaches
• Waking to urinate more than once a night
• Nocturnal sweating
• Hypertension that is harder to control than expected
• Neck circumference over about 17 inches

A home sleep apnoea test is now cheap, does not require a lab, and takes one night. In most cases there is no reason to guess.

If you do get testosterone tested, test it properly

• Morning, fasted, before 10am. Testosterone follows a daily rhythm and afternoon values in younger men can be materially lower.
• Two separate mornings. A single low reading is not a diagnosis. Day to day variation is large enough to move a man across the reference cutoff.
• Ask for LH, FSH, prolactin and SHBG alongside. Total testosterone alone does not tell you whether the problem is in the testes or in the pituitary, and those two situations are managed very differently.
• Ferritin, thyroid and HbA1c. Iron deficiency, hypothyroidism and early insulin resistance all produce the same fatigue picture.

What actually shifts the number

Sleep is the highest-leverage variable and the one most men skip past because it is not purchasable. Beyond that, fat loss in men with obesity raises testosterone in a fairly dose-dependent way, resistance training and adequate protein support it, and heavy chronic alcohol intake suppresses it.

None of this is exciting, and all of it is free.

On research compounds marketed for this

Growth hormone secretagogues and various peptides are marketed heavily into this exact feeling, usually to men who have not had a sleep study or a second morning blood test. Whatever the preclinical literature says about any of them, none of it addresses an untreated airway closing a few hundred times a night. Treating the marker while the mechanism runs untouched is the expensive version of doing nothing.

FAQ

Can sleep apnoea cause low testosterone?

Yes. Testosterone secretion is concentrated in sleep and tied to sleep continuity. Apnoea fragments sleep repeatedly through the night, and treating the apnoea can raise testosterone without any hormonal intervention.

Should I get a sleep study before starting testosterone?

It is worth doing. Testosterone therapy can worsen untreated obstructive sleep apnoea, and clinical guidance treats untreated severe apnoea as a reason to delay starting rather than proceed.

What time should testosterone be tested?

In the morning, before 10am, fasted, and on two separate days. Testosterone follows a daily rhythm and single readings vary enough to be misleading.

What else should be tested alongside testosterone?

LH, FSH, prolactin and SHBG, which distinguish a testicular cause from a pituitary one, plus ferritin, thyroid function and HbA1c, since all three produce overlapping fatigue symptoms.

Does losing weight raise testosterone?

In men with obesity, yes, and roughly in proportion to the weight lost. Adipose tissue converts testosterone to oestradiol, so reducing fat mass shifts the balance.

Why do I feel tired when my labs are normal?

Normal labs rule out a short list of causes. They do not rule out fragmented sleep, which is not measured by a blood test and is the most common explanation in men whose bloods come back unremarkable.

Sources

• Endocrine Society clinical practice guideline, testosterone therapy in men with hypogonadism.
• Wittert G. The relationship between sleep disorders and testosterone in men. Asian Journal of Andrology.
• Luboshitzky R et al. Disruption of the nocturnal testosterone rhythm by sleep fragmentation in normal men. Journal of Clinical Endocrinology and Metabolism.
• American Academy of Sleep Medicine clinical practice guideline, diagnostic testing for adult obstructive sleep apnea.

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