What makes you think he is having nocturnal emissions? I've never heard of such a thing. THis is a normal part of adolescent development associated with a build up of seminal fluid and can occur every two to three weeks AT MOST... Obviously that is not the case with your husband.
Did HE tell you he is having wet dreams?
Did you find stained underware?
Are we talking the same thing here? I don't think we are. Sorry I just don't buy it.