My advice is don't touch it....
Like many of these hormones we all wish to get into our bodies many of them peak at about your age and then decline there after. DHEA, testosterone, melatonin, GH etc... typically decline from here on out for you, but this decline is minimal and for you to use these hormones at this age will only cause this "decline" to be greater.
Just about all hormones have a negative feedback loop(some don't) this basically means if I take something that will tell my body there is something there without the body producing it well then the body won't produce it. That's why everyone cycles AAS, PHs and GH. We don't want to shutdown our bodies from producing these hormones.
HGH also plays some weird roles within the body.