Without sex in the equation I believe Steve is correct. Google says: Best Time of Day for a Testosterone Test. Doctors often recommend that men with erectile dysfunction have their testosterone measured from 8 a.m. to 11 a.m., because levels are usually highest then and vary over a 24-hour period. But a new study has found that this variation occurs only in younger men
The argument against that is that one study doesn't disprove f' all