Testosterone - Less Sleep Means Less
Many things happen at night - especially when you dream.
Posted June 9, 2011
Yep, it's true - give healthy young men less sleep time and down goes the testosterone (though not irritability.) The data come from the University of Chicago, where checking hormone changes wrought by sleep deprivation has become a minor research industry (http://news.consumerreports.org/health/2011/06/sleep-deprivation-may-lo…).
The guys studied were young - average age 24. They slept 10 hours for the first three nights, then 5 hours the next 8 nights, with careful blood monitoring of many different hormones throughout the day and night. It's been known for quite a while that insulin, ghrelin, and leptin go haywire with the kind of partial sleep deprivation common among undergraduates. To this list we can now add testosterone.
Why Does Sleep Deprivation Lower Testosterone?
Sleep is required for body regeneration. Beyond teeth, bone, and bunches of cytoskeletal proteins, you replace most of yourself within 3-4 weeks. Yes, you're a lot younger than you think. Cut sleep down a bit, especially below the level of six hours, and people develop insulin resistance, gain weight, and experience much physiological underperformance - making you feel your real age.
Yet there's another striking reason why testosterone level lowers with less rest - the peculiar actions of REM sleep. REM is where you get peak, pulsatile production of testosterone - with every REM episode.
Normally we get three to five REM episodes a night, with the largest and longest period going perhaps an hour right before we wake up. Which is why the gold standard for determining whether someone has erectile dysfunction is putting them into the sleep lab and testing penile pressure during REM. The procedure has become far less common since the advent of drugs like sildenafil (Viagra) but it does explain why REM sex can be a productive, entertaining sideline for many couples (see my book "The Body Clock Advantage" for further details.)
So - less REM sleep, less peak testosterone. Mind you, when people are partial sleep deprived they tend to preserve when people are systematically sleep deprived they try to keep on as much REM and deep sleep as possible. Still, as the sleep debt accumulated, you will have less REM - and less testosterone.
Why Should We Care About Producing Less Testosterone?
If you've been watching television or reading the popular press for the last few years, testosterone has been much touted to help "decrease" aging and return men (and some women) to past youthfulness. Testosterone does decrease with age, and professional sports is sufficiently impressed by its muscle building prowess that it is banned as a doping agent.
Certainly testosterone has multiple effects. Beyond setting up much of normal "secondary" sex characteristics, it tends to give people more brawn, more muscle, and produces complicated effects on clotting pathways.
Whether testosterone really does help return aging adults to relative youthfulness is a thorny matter. Since hormones generally have hundreds of physiological effects, effects intensely mediated through other hormones, possess many, generally unknown long term results when applied as medical treatments (witness the heart disease and breast cancer disaster of female hormone replacement therapy,) the present trend to reward aging males with added exogenous testosterone might turn out sadly. There are literally thousands of variables one might want to know adding testosterone into life's daily mix. Doing such studies is difficult and expensive - which means in the main they won't get done.
Is there evidence testosterone is good for you? Certainly. There's fair evidence it helps the mood of older, depressed males, and many older men rave about its usefulness, though many researchers consider the effects not better than placebo.
But this Chicago study was performed in young men. Your average 24 year old should have nice, high levels of testosterone - and its effects - to enjoy. We can hope that as the study subjects returned to "normal" sleep, their fillup of male hormone rose accordingly.
Change sleep and you change most human physiology. Rest is regeneration. If you don't get enough of it, you don't regenerate properly - and that includes brain as well as muscle.
Too little sleep means too little testosterone. So here is yet another reason for professional athletes to protect their sleep time in order to learn more (including muscle memory) and improve performance.
But don't feel too bad if testosterone lowers temporarily. That's what happens when men fall in love - a potential delight for all concerned.