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What Causes What
MECHANISM+ INCREASES

Sleep duration and regularity → Testosterone

Higher Sleep duration and regularity increases Testosterone.

In men, experimental sleep loss lowers testosterone. A week of 5-hour nights cut daytime T about 10 to 15 percent. One night of total wake cut 24-hour T. All-night deprivation cut total T; REM-only did not. In 37 healthy adults, T also fell during long wake; caffeine lessened that drop.

Randomized trial · Moderate · N=35

Supported by an experiment or a tightly identified design. Read the caveats.

Mechanism

Leproult and Van Cauter kept ten young men on 5-hour nights for a week. Daytime testosterone fell. Cortisol did not fall with it in that protocol. Liu, Takahashi, Yang, Iranmanesh, and Veldhuis then kept 35 men awake all night or let them sleep from 10 pm to 6 am, in random order. Mean, basal, and pulsatile 24-hour testosterone fell, and pulse frequency fell, without a matching drop in luteinizing hormone across the day. The change was clearer in the men aged 60 to 80. The authors read this as a time-of-day uncoupling of testicular control, not a simple LH drop. Faraut, Andrillon, Drogou, Gauriau and colleagues also saw morning salivary testosterone fall after two 3-hour nights, but only when each man was compared with his own habitual sleep. The factor they randomized was blue light after the short nights. Alvarenga, Fernandes, Bittencourt, Tufik, and Andersen compared men who already had obstructive sleep apnea with healthy volunteers, then randomized the healthy men to total or REM deprivation. The apnea contrast is who already had the syndrome. After total sleep deprivation, total testosterone fell. After REM-only deprivation, it did not. Sperm counts did not move after either deprivation. The abstract does not say how many men were studied. Drogou, Sauvet, Erblang and colleagues kept 37 healthy people awake and randomized caffeine against placebo. Testosterone and cortisol both fell during that wakefulness. Caffeine lessened the testosterone drop. What they randomized was the caffeine, not sleep versus sleep. The testosterone change is the drop during wake, the same kind of contrast as Faraut's restriction-versus-baseline. Drogou's headline was IGF-1 and a gene variant. Testosterone was a measured hormone during the same wake.

Caveats

The protocols are still short. The longest lasted a week. Liu compared one night of total wake with 8 hours in bed. Alvarenga's abstract does not report N. A clinical-trial listing is not the paper. The apnea arm is not a randomized sleep contrast. In Faraut and in Drogou, testosterone fell during short sleep or long wake against each person's own baseline. What they randomized was blue light or caffeine. Drogou also saw cortisol fall; that is not this arrow. Most of the samples are men. Five papers do not make the stamp more certain.

Effect

percent_change = -12. Leproult 2011: about 10 to 15% lower daytime T after 5-hour nights (N=10 men). Liu 2021: overnight wake lowered 24-h T (N=35 men). Alvarenga 2023: total T fell after total, not REM, deprivation.

Nodes

Lifestyle & environmentSleep duration and regularityBiology & endocrinologyTestosterone

Cite this page

What Causes What. “Sleep duration and regularity → Testosterone.” https://whatcauseswhat.org/edges/e-sleep-testosterone (atlas updated 2026-09-02).

https://whatcauseswhat.org/edges/e-sleep-testosterone

Papers