Do ssri permanently deplete serotonin receptors?

So once person is off ssri, their serotonin levels are low and can't get back to the way they were before taking ssri? And what is considered long term ssri usage? I've been on ssri such as paroxetine for 10 months, i weaned myself slowly, so i didn't have any side effects, but 2 months later i started to suffer from insomnia ( trigger was stress), could it be because of low serotonine levels?thanks!