Ask the Doc.
Q:
What is 'morning wood' caused from?
A:
Presumably you are referring to morning penile erections that most men wake up with?
This is a combination of full bladder causing nerve stimulation resulting in a sometimes inconvenient erection, especially when you need to urinate, and sometimes related to autonomic nervous system response to dreams.
It is normal, an indication that there is no physiologic problem with the ability to get an erection, and goes away spontaneously shortly after waking up.
Sarah
Reppin' 907