I cant say i've noticed more spooky sounds at night.
Noise is more noticable when theres nothing else you're focusing on, since you mentioned only hearing them when attempting to sleep that would be my guess.
Also yeah what user above mentioned could definently be a factor that the goons come out at night
because the sounds of the day (animals, car engines, construction, some aircraft) aren't present at night and any remaining sounds will stand out more
also humans instinctually associate night with danger
wiitard