I found mine fairly okay, without sedatives or numbing, but I was fortunate to be able to access a specialist genitourinary health centre and the doctor doing the procedure communicated well. A lot of the bad stories I've heard stem from inconsiderate or inept doctors.

This is just one anecdote from a doctor friend, but she firmly believes that sedatives or numbing should rarely be necessary if the person doing the procedure is good at it (and she says many in general practice aren't good at it because they do it so infrequently and they also don't care to learn more). Something notable is that my friend considered herself decent at fitting IUDs relative to other general practice doctors, but this conversation started when she told me about the optional supplementary training course she had paid for herself, to be better at it. She felt the extra training should be the minimum required.

I would have liked to have had the option of sedation though, with my IUD, even though it went fine. I asked about the possibility and I was told it wouldn't be necessary and I was anxious at that point because I didn't know whether my doctor was trustworthy, given the abundance of stories online where doctors are dismissive around IUD insertion pain.