> Studies have shown that just one week of sleep deprivation—less than five hours per night—dropped young male’s testosterone levels by a whopping 10 to 15 perc

> Studies have shown that just one week of sleep deprivation—less than five hours per night—dropped young male’s testosterone levels by a whopping 10 to 15 percent. For comparison, a healthy individual’s testosterone will naturally decline by 1 to 2 percent per year. In other words, as far as your hormonal system is concerned, a week of bad sleep will age you a decade. But isn't this temporary, not permanent? I was repeatedly sleep-deprived as a military officer in my 20's -- both chronically and acutely, and often beyond the parameters described in the article -- and my T levels are normal now that I'm in my late 30s.