Reynolds · Sleep 1989 · cross-sectional observational study · n=48

Nocturnal penile tumescence in healthy 20- to 59-year-olds: a revisit.

Cited 23 times in the scientific literature.

Level 4 - case-series / case-control

Cross-sectional normative observational study in healthy volunteers

PubMed 2762691 · record verified 2026-08-27

What was done

Assessed normative nocturnal penile tumescence (NPT) parameters in 48 healthy men aged 20 to 59 years with no complaints of erectile dysfunction. Evaluated electrographic NPT measures, visual estimates of erectile fullness, and buckling force estimates of penile rigidity across four age decades.

What was found

Pathology-free aging between ages 20 and 59 accounted for a modest 8.4% to 14.4% of the variance in electrographic NPT measures. There were no age effects on visual estimates of erectile fullness or buckling force estimates of penile rigidity. Maximum buckling force and maximum erectile fullness remained stable across all four decades evaluated.

Why it matters

Provides normative reference data showing that intrinsic physiological erectile capacity and rigidity during sleep remain largely stable across mid-adulthood in the absence of disease.

Limits

Small sample size (48 men across four decades), cross-sectional design without longitudinal tracking, limited to healthy men up to age 59, and specific numerical means or confidence intervals are omitted from the abstract.

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