  K\'arolyh\'azy's original proposal, suggesting that space-time fluctuations
could be a source of decoherence in space, faced a significant challenge due to
an unexpectedly high emission of radiation (13 orders of magnitude more than
what was observed in the latest experiment). To address this issue, we
reevaluated K\'arolyh\'azy's assumption that the stochastic metric fluctuation
must adhere to a wave equation. By considering more general correlation
functions of space-time fluctuations, we resolve the problem and consequently
revive the aforementioned proposal.
