OtherHumann = 102001
Disruption of the nocturnal testosterone rhythm by sleep fragmentation in normal men.
Plain-language summary
This study asked whether the nightly rise in testosterone is driven by sleep itself or by the body clock. Ten men went through an ultrashort schedule of seven minutes asleep and thirteen minutes awake, repeated for a day, which both fragments sleep and cuts it short. Their testosterone was sampled every twenty minutes from 7pm to 7am, and the results were compared against men sleeping continuously. Average levels across that window were similar in the two groups, but on the fragmented schedule the nightly rise came about five hours late, and it appeared only in the four men out of ten who managed to reach REM sleep in the seven minute windows.
Key findings
- On the fragmented schedule the nightly testosterone rise came at 03:24 against 22:35 in men sleeping continuously, about five hours later.
- The rise appeared only in the four men out of ten who reached REM sleep during the seven minute sleep windows.
- Average testosterone across the sampling window was similar in both groups.
- Testosterone was sampled from 7pm to 7am, so this covers the evening and the night rather than a whole day.
How to analyze the study yourself
- Study type
- This is a laboratory paradigm built to break sleep apart rather than to imitate a bad night, which is what lets it separate the timing of the testosterone rise from the clock. The trade is that seven minutes asleep and thirteen awake is not a night anyone actually has.
- Population
- Healthy men without sleep disorders
- Funding
- Not reported
- Takeaway
- This study found that when sleep was chopped into seven-minute pieces, the nightly testosterone rise arrived about five hours late, and it appeared only in the four men out of ten who managed to reach REM sleep at all. Sleep and testosterone are tied together at the level of sleep quality and not just hours in bed, because the rise seems to wait for REM.