Washington: Cutting back on sleep can be quite disastrous for healthy young men - it sends their testosterone levels plummeting, says a study.
Men who slept less than five hours a night for one week in a lab had significantly lower levels of testosterone than when they had a full night`s sleep, according to the study.
Significantly, skipping sleep was found to reduce a young man`s testosterone levels by the same amount as aging 10 to 15 years, or 10 percent to 15 percent.
Low testosterone has a host of negative consequences for young men, and not just in sexual behaviour and reproduction. It is critical in building strength, muscle mass and bone density.
"Low testosterone levels are associated with reduced well being and vigour, which may also occur as a consequence of sleep loss," said Eve Van Cauter, professor in medicine, University of Chicago Medical Centre, the US, who led the study, according to a Chicago statement.
At least 15 percent of the adult working population in the US gets less than five hours of sleep a night, and suffers many adverse health effects because of it. Low testosterone is also linked with low energy, reduced libido, poor concentration and fatigue.
The group of young men recruited for the study passed a rigorous battery of tests to screen for endocrine or psychiatric disorders and sleep problems. They were an average of 24 years old, lean and in good health.
They spent three nights in the lab sleeping for up to 10 hours, and then eight nights sleeping less than five hours. Their blood was sampled every 15 to 30 minutes for 24 hours during the last day of the 10-hour sleep phase and the last day of the five-hour sleep phase.
The effects of sleep loss on testosterone levels were apparent after just one week of short sleep. Five hours of sleep decreased their testosterone levels by 10 percent to 15 percent.
The young men had the lowest testosterone levels in the afternoons on their sleep restricted days.
They reported a decline in their sense of well-being as their blood testosterone levels declined. Their mood and vigour fell more every day as the sleep restriction part of the study progressed.