I used to live on my own for several years, in a house ~100 years old. It rarely bothered me, tbh; but then I started hearing noises late at night. Turned out I had rats and they were gnawing the floorboards around the pipes for the radiators. I ended up with proper Tom & Jerry style holes in the floor/skirting boards!
Before I worked out what it was though, I made sure I had my halogen maglite torch by my bed at all times - blind any burglars first then hit them over the head if they came close enough. Also, phone by the bed.
Now, I occasionally get bothered if DH is away; but he doesn't need to be away for me to get the heeby jeebies!
A couple of weeks ago, I woke to a sudden noise, couldn't work out if I'd really heard it or dreamt it, sounded like muffled footsteps going through our single storey house, only not, because they were muffled and we have floorboards. No lights visible (my door is ajar) and no strange other noises. Went back to sleep after having a word with myself. Jolted awake again shortly after by the same sort of noise, heart hammering etc. - but nothing.
Told DH about it next day - he said he'd heard it too! We decided it was either a ghost (Ha!) or a rat in the roof.
THEN at the start of this week, middle of the night I was woken by noises - sounded like DS1 (8) had come out of his bedroom, tripped over some bags/cases on the floor and scuttled to the loo. So I got up to check he was ok (he almost never does this unless he's ill) - no lights on, how odd.
Then I heard noises among the toys in the living room - wondered if DS1 was sleep walking!
So I put the main light on - no Ds1 - how very odd!
Walked right into the living room, heard the noises again and then realised there was a fuck-off big possum in among the toys!
NO idea how he got in. Woke DH, who said "ah leave it"
and then went straight back to sleep, leaving me to evict the possum. Which actually went fairly well, tbh - it seemed stupendously unbothered about me being there, rather like a superior sort of cat - I opened the back door and ushered it out (in its own time).
STILL no idea how he got in. None.
Mostly I'm not bothered though. Mostly.