'Looks like it's been quite awhile since anyone posted on this one. Maybe this info will cast some more light.
At age....(uhhh---mid to upper 40's), I have noticed some change in the frequency of morning erections. Several comments already posted seem to be true:
(1) Testosterone levels "peak" in the early morning hours and would certainly have the potential to impact erections.
(2) Frequency of using the penis (intercourse and self-pleasuring) could (and probably does) lessen the body's need for "morning wood".....more on that in a moment
(3) Morning erections tend to lessen as we get older.
(4) As with everything else with the male organ (i.e. size, shape, etc) the frequency of morning erections varies from man to man...
(5) The "medicine boys" do have ways of testing men for impotency by way of monitoring nighttime erections with paper strips and their fancy gadgets, etc....Many of these "patients" are pleasantly surprised, too, when they are told they DO still get hard when they thought they didn't....Isn't modern medicine wonderful?
"Morning Wood" --why does it occur? My reading (not a heavy researcher, mind you--but I have done considerable reading) indicates it is thought the penis requires "deep enriching amounts of blood periodically to stay in good form and remain able to function".
DA ! (yawn) ...nothing new!
Mysteriously, if the penis does not get this from use (via strong erections for considerable lengths of time), then the body is wise enough (somehow) to prompt or induce an erection(s) --often several during the night to "refresh" the blood supply in the penis. So, (apparently) it's really quite a natural response and is not necessarily related at all to mere sexual arousal (i.e. wet dreams or the like which we men experience earlier in life.) And, some will attest here in the forum that, even with regular sexual activity, morning erections still occur frequently. Why? --Perhaps higher amounts of testosterone in the system? --Could be. Who knows?
But, studies do show that as men age, testosterone amounts begin to diminish over time. Prostate health must be monitored. Erection strength and libido also can diminish gradually; ever so gradually, over time.
Many men find nutritional supplements added (responsibly) to their diets help sexual performance and overall sexual health. (I speak from experience, here and have noticed an increase in libido, erection improvement, more forceful ejaculation and improved semen quantity, and yes--more frequent morning erections. In addition to supps. I should also mention that I perform maintenance jelqing as well) --All of it has benefited me, I have no doubt, whatsoever.
It's worth considering help and solutions I think for any man who's noticing changes which begin to concern him, --no matter the age. Afterall, sex is an important part of our lives. Why NOT seek info on how to keep everything in "good working order"?