Night time erections usually happen during REM and have nothing to do with sex. Towards morning, a lot of times you have to urinate and that will cause an erection. Day time erections are purely psychological, unless you get direct stimulation. Totally different from night time erections. I agree with Matrix on this one, that low test doesn't mean you can't get it up. Now if you took Deca, I'd say that's what you get!