Try. Respectively lie down under the bed and let someone the top of the bed move then you see the problem
I also had. Have solved with window weatherstrip the problem. Simply glue under the grate, or on the bed frame.
I've found with me that the slatted frame shifts sometime. How do I place the ... well ....
Usually I set the then and then it's back until it moves again. In my bed is really about a millimeter. Moves itself as a mere trifle, fit do nothing more.
But it may also be that this is a normal sound which is given you only noisy because you can not sleep. Will you wake them?
Could be that the grate is in the air and slams on the bracket.
Have you checked the grate?
Villeicht he is already halfway.
Take hold the mattress down and look after.
reduce weight ? the latte frame haltering firmly on the? then solve unilaterally.