Meditation and Nightmares

Hello all! I wasn't exactly sure where to post this, really. I had a friend who died from suicide back in October. I stopped having nightmares about her wake for a good while, but they came back again. Do you think it would be okay if I meditated on a Bodhisattva (Guanyin) for example before I went to sleep to try and deter these nightmares? I hope I asked this question in the right place. I was going to ask r/Buddhism but decided to ask it here instead.

Thank you!