Testosterone is a male hormone which regulates sexual activities, development of bones, muscles, bone density, sperm and red blood cell production. In men, testosterone level keeps on falling with age. When an individual suffers from low testosterone levels, he is likely to experience a reduced sex drive. This implies that the man does not feel like getting involved in sexual activities like normal men do. The person may also become infertile and experience irregularity in sleeping pattern. Other symptoms of low testosterone levels include emotional changes and sexual dysfunction. Some of the most common causes of low testosterone levels in males include injury that affects the testicles, medical conditions, such as testicular cancer, and diseases like HIV/AIDS, chronic liver and kidney disease, hormonal issues and being overweight. While it is quite natural for men to experience a low in testosterone level, required treatments can help in curing the above-mentioned problems completely.