Testosterone is the primary male hormone which is important for male libido and energy levels. According to a recent study of 12 healthy men between 64-74 years of age, it was found that the amount of sleep an older man gets may affect his morning Testosterone levels in the blood. It was also revealed that the amount of sleep received at night predicted the morning Testosterone levels in men.
SLEEP vol 32(7)-Jul. 01, 2009