From Featuring Dr Chris Steele MBE

Lack of sleep affects young men's sex drive

Effects seen in less than a week

Young men who cut back on their sleep hours may also be drastically reducing their testosterone levels, according to a new study.

Testosterone affects more than just libido, it plays a vital part in building strength and muscle mass, as well as bone density. Getting less than 5 hours sleep per night reduced the sex hormone's levels by between 10% and 15% - equivalent to the drop experienced as men age over a decade.

In the study, 10 young male students at the University of Chicago spent 11 nights sleeping in laboratory conditions. For the first three nights they slept for up to 10 hours, and in the remaining 8 nights they slept for only 5 hours.

All the men in the study had passed a rigorous battery of tests to screen for endocrine or psychiatric disorders and sleep problems, and they were on average 24 years old and in good health.

At the end of the 3-day period with full sleep the men's blood was sampled every 15 to 30 minutes for 24 hours. This was repeated at the end of the 8-day reduced sleep phase.

Over this time the effects of sleep deprivation on testosterone levels were immediately evident, with the drop of 10% to 15% being recorded between the two sets of readings. The young men had the lowest testosterone levels in the afternoons on their sleep restricted days, between 2pm and 10pm.

Commenting on the results, study leader Eve Van Cauter said: "Low testosterone levels are associated with reduced well being and vigour, which may also occur as a consequence of sleep loss". This was echoed by the men in the study, who reported that their mood and vigour fell more every day as the sleep restriction part of the study progressed.

These results are worrying as an estimated 15% of men gets less than 5 hours sleep each night, as Van Cauter explains: "As research progresses, low sleep duration and poor sleep quality are increasingly recognized as endocrine disruptors."

The results are published in the Journal of the American Medical Association.

This article was published on Wed 1 June 2011