I've read the Quantum Zeno (QZ) Effect is caused by Quantum Decoherence (QD), and that QD is, in general, a representation of the wave-function collapse of a quantum system (the Wikipedia explanation on this is confusing to me, to say the least). If I understand the QZ Effect correctly, unitary time evolution is suspended for the quantum system undergoing the QZ effect. An example of the QZ Effect that I am familiar with is an unstable atom which does not decay during observation, which would have otherwise already decayed. It would seem to me the wave function of the atom in this example, while under observation, is still intact and has not yet "collapsed", correct? If my understanding here is correct, what then does QD have to do with the QZ Effect? QD seems to involve wave-function collapse, while a system undergoing the QZ effect, there is no wave-function collapse. What am I missing here?