OP, have you gotten blood work to see your total and free testosterone levels? There are many anecdotes of HCG improving mood and libido in people. There are receptors in the brain for Luteinizing hormone and hcg. Theoretically, this means HCG may have some effects on mood and brain function. There is also the theory that hcg can increase some other hormones like pregnelone and DHEA which can affect mood, energy and libido. No hard science here, just conjecture, but some of these may explain the effect hcg has on some people.