I’m sorry to hear you have trouble sleeping - intrusive thoughts before sleep are a symptom of insomnia which like all ailments of the mind have triggers.
Humans are social creatures of habit any deviation from the norm or any situation which causes you anxiety is dealt with what psychologists call System 1 thinking - which is the part of your brain that deals with survival.
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Now I can’t really comment on fear of sleeping - I’ve slept in the back of a container in the middle of nowhere on more than one occasion and your brain gets used to that.
If you find sleeping in unfamiliar settings concerning - try to take something with you that reminds you of home- it can be a small decorative item - a scented candle or your own pillow case.
Other coping mechanism are to leave a nightlight on or leave the TV/ Radio playing in the background.
You may think that these coping strategies are nonsense but there is science behind them.