Can one week of 5-hour nights lower testosterone 10–15%?
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Does one week of short sleep lower testosterone?
In one University of Chicago lab study, 10 healthy young men spent 3 nights with 10 hours in bed, then 8 nights with 5 hours in bed.
Blood drawn every 15 to 30 minutes showed daytime testosterone fell from 18.4 to 16.5 nmol/L, and from 17.9 to 15.5 between 2 and 10 PM.
Most of a man's daily testosterone is released during sleep.
Sources
Leproult R, Van Cauter E. Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA 2011;305(21):2173-2174. doi:10.1001/jama.2011.710
What the study says
- “After 1 week of 8-hour bedtimes (from 11 PM to 7 AM) at home, the participants spent 11 days in the laboratory for 3 nights of 10-hour bedtimes (from 10 PM to 8 AM; rested condition) followed by 8 nights of 5-hour bedtimes (from 12:30 AM to 5:30 AM; sleep restriction).”
- “Blood sampling every 15 to 30 minutes for 24 hours was initiated after the second 10-hour night and after the seventh 5-hour night. Samples were assayed for total testosterone and cortisol”
- “Total (SD) sleep time decreased from 8 hours 55 minutes (35 min) to 4 hours 48 minutes (6 min) with sleep restriction (P =.002).”
- “During waking hours common to both conditions (8 AM-10 PM), testosterone levels were lower after sleep restriction than in the rested condition (16.5 [2.8] nmol/L vs 18.4 [3.8] nmol/L; P =.049). The effect of restricted sleep was especially apparent between 2 PM and 10 PM (15.5 [3.1] nmol/L vs 17.9 [4.0] nmol/L; P =.02).”
- “Daytime testosterone levels were decreased by 10% to 15% in this small convenience sample of young healthy men who underwent 1 week of sleep restriction to 5 hours per night”
Where it falls short
One small study, compared with 10-hour nights.
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