you must have watch too much incredible tales, or read too much
ghost stories.
personally i have invited spirits up from down there to ask
questions, if you bump into any, just treat them with the respect
like they treat you (by doing nothing; no reactions needed) and
walk off then they will also return you the favour too
if your really scared to bump into any in your bunk, then i suggest
that you don't sleep Near the windows, the fan, the ceiling
windows are form of passage way for spirits to pass through, the
same goes to ceilings, as for fans, in case you have nightmares
associated with those ghost stories that you came upon in your
dreams la.
if you really can't sleep:
listen to radio
drink hot milo/ cold milo, which ever will make you sleep better or
perhaps a glass of hot milk
go for a shower, when your skin are feeling cool, it's easier to
sleep
read a book that will make you sleep (recommended if you dislike
reading books)
turning on the lights in your bunk will only make the CSM and SGTs
punish you only.. (try not to switch on the lights, while trying to
get used to it)
Don't think too much, when you are trying to sleep, think of
absolutely Nothing, as your brain should be resting, if there is
activity, naturally you will not be able to sleep, logic ma.
hope it helps