Well something isn't right then with my bluetooth controller in the console then if thats the case.
I sit about 8-10 feet away but the console has to transmit through a very high quality mattress (£1400) as it's lower down than the bed. Console is in the bedroom.
I have 2 DS4's and I have issues on both from time to time in voice comms (when i use the controlle rove rmy mixamp) and also the controller starts moving by itself. e.g. My character on screen will start aiming up/down when i'm not touching anything, until I move closer then go back again.
Oh lawd, unless your "£1400 very high quality mattress" is made from lead, then that won't be causing the signal to degrade (as an aside, a mattress's cost doesn't indicate its quality, it indicates that you've been ripped off).
What is probably happening is that you're getting some sort of interference from something else.