Why are some people able to sleep through loud noises and others aren't?

Question

Why are some people able to sleep through loud noises and others aren't?

Answer 1

Some people seem to be like cats.. they wake up at the slghtest noise. . me i guess I would sleep if the house was swept away as in '' the Wizard of Oz and Dorothy had the dream that this was happening... when i am asleep only a phone call or the doorbell would wake me any time.. or the alarm clock of course.. others.. they wake up if you only move..  x Sometimes people have a lot on their mind.. stress. that will cause insomnia.. and some are like that always for no particular reason.. they can't sleep well.

Answer 2

I honestly think they go into a very deep sleep and their ears turn off.  I used to not believe there was such a deep kind of sleep until I had a fire in one of my rentals.  The alarm was blaring, fire sirens screaming up the street and I was pounding on one of my tenant's doors to evacuate her and she heard none of it!  I had to physically go inside her unit and shake her awake to get her out and I was screaming her name from the time I opened her door.  She just had some kind of ability to turn off her hearing when she slept.