You have cats. Do they go under your bed? Has the fabric under box spring bee ripped up by kitties?
little spiders love to live inside box springs and seek warm blood at night.
If you can, replace the box spring.
If not take it out doors, rip all that messed up fabric off, spray inside with spider killer of your choice. Let the the thing air out for 24 plus hours and do it again.
Get some hessian or muslin or a fitted sheet and a good upholstery stapler and recover the bottom of the box spring.
while the bed is outdoors, bomb your room and check nooks and crevices especially behind and under furniture where the little buggers can ihide.