I think this notion has become popular because of the news about what nurses do.

I have heard this statement a well and have tried to ask around. I think the answer is psychological.

Yes. The thing is this. Nurses are trained to show care and compassion to patients irrespective of how they feel or what they think about the patient. They smile and carry out their duties with an attitude that makes it seem like they are always on joy mood.

Now, for most men, what attracts them to women is the way they carry themselves, their respect and cleanliness. All of these attributes are exhibited by nurses. So, the attraction usually happens, at times, naturally.

Also, some men have their love language as touch. So, the nurses when treating their male patients may be unconsciously triggering their emotions.

This is not to say that the issue is only due to the male folks. Some nurses, because they know what to do in case of infections or pregnancy, will deliberately go after every thing in trousers.

These are the reasons I can think of.