Is job-shadowing a better, or adequate alternative to internships?

I have struggled to find internships that are more than vaguely connected to the line of work that I wish to pursue when I complete my degrees. I am wondering, would it be an effective alternative to contact someone in the position that I want to be in and ask about job-shadowing for some time - essentially, seeking out an unpaid internship, where they haven't officially asked for one?