You are at your desk before most people and still answering messages after dinner. You train when the diary allows. Output is high, yet focus, drive and recovery are not what they were.

Most men put this down to the job, a heavy quarter or simply getting older. Sometimes that is right. Often it is a measurable pattern hiding behind a reasonable excuse.

The metric nobody is tracking

You track revenue, pipeline, sleep scores and training load. The system running all of it rarely gets measured. Afternoon focus drops off, recovery takes longer and the edge in a negotiation is not quite there.

None of this arrives as one dramatic symptom. That is exactly why it gets ignored.

What short nights do to testosterone

Most of a man's daily testosterone release happens during sleep. In a University of Chicago study published in JAMA, healthy young men who slept five hours a night for one week saw their daytime testosterone fall by 10 to 15 per cent.

The researchers compared that drop to the effect of ageing 10 to 15 years. The lowest levels fell between 2pm and 10pm, the hours when most executives are still expected to perform. It was a small study of ten men, but the direction is hard to ignore.

Cortisol and testosterone pull in opposite directions

Cortisol is the hormone that gets you through a demanding day. Kept high for too long, it works against you. Researchers at the University of Texas at Austin describe the systems regulating cortisol and testosterone as antagonistic, with chronically elevated cortisol able to inhibit testosterone production in men.

This lands on top of a slow baseline decline. Research puts the average fall in testosterone at around 1 per cent a year from about age 30. A man in his forties is already working with a shrinking reserve, and sustained stress with short sleep draws on it faster.

DHEA, the reserve you never see

DHEA is a building block your body uses to make testosterone and oestrogen. A 2013 review in Rejuvenation Research found that DHEA falls with age in both men and women, sometimes to 10 to 20 per cent of the levels seen in young adults.

A standard check-up rarely looks at it. It is one of the clearest signals of how much capacity you have left in reserve.

Why one blood test misses the pattern

A single morning blood draw gives you one number at one moment. A DUTCH test is collected as dried urine samples across a full day. It maps how your cortisol rises and falls, how much DHEA you produce and how your body processes testosterone, including how much is converted into its more potent form, DHT.

That is the difference between a snapshot and a dashboard.

Good data knows its limits

In most men, urine testosterone closely reflects the free testosterone seen in blood. Some men carry a common genetic variation, a deletion in the UGT2B17 gene, which means very little testosterone appears in their urine whatever their blood levels are.

In a study of Swedish and Korean men, every man carrying two copies of this deletion had no or negligible urinary testosterone. The variation was found in 9.3 per cent of the Swedish men and 66.7 per cent of the Korean men. That is why a very low urine result is always confirmed with a blood test before drawing any conclusions.

Working from numbers, not assumptions

Once the pattern is visible, the plan becomes specific. It might be sleep, training load, how and when you eat, or how much recovery your week actually allows. If anything points beyond nutrition and lifestyle, that conversation belongs with your doctor, and you walk in with data.

You would not run a business without a dashboard. There is no reason to run yourself without one.

Want to see exactly what the test measures? Download The Dutch Dozen, my free guide. 

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Sources:

• Leproult R and Van Cauter E, JAMA, Effect of 1 Week of Sleep Restriction on Testosterone Levels in Young Healthy Men, 2011
• University of Chicago Medicine, Sleep loss lowers testosterone in healthy young men
• University of Texas at Austin, Stress hormone blocks testosterone's effects, study shows
• Acta Biomedica, Review of testosterone decline in the ageing male
• Rejuvenation Research, A review of age-related dehydroepiandrosterone decline and its association with well-known geriatric syndromes, 2013
• Frontiers in Endocrinology, UGT2B17 genotype and urinary testosterone excretion, summarising Jakobsson et al. 2006
• Precision Analytical, What does the DUTCH test measure?