Meditation Retreat Question

I have been following your (yuttadhammo) videos for some time. I had a question that I wanted to ask to someone who is experienced and familiar with meditation and Buddhism. I went to a 60 day meditation retreat in Myanmar last year. I had a great experience there and so as a result I am planning to go back again for 4 months at the end of this year. I have had some experiences during my last trip which puzzled and scared me a bit. I was disturbed on a couple of occasions by beings from other world at night. These were scary experiences that scared me to the core during the retreat. It was difficult for me to meditate and to fall asleep at night as my mind would always stay in that defense mode where it wouldn't relax and fall asleep. I talked to the teachers about it and they said to practice metta meditation and to ask these beings to not disturb my meditation. They also asked me to not be afraid and simply watch the fear. It did that and it did work for the time being but the fear overpowered me during the entire retreat although I am glad that I was able to make some good progress. I want to be better prepared this time around when I am going back again. My question is what can I do better this time so I can be well prepared and so the fear of being disturbed again does not overwhelms me? I would like to practice meditation this time by leaving fear behind. Thank you for reading this.