Predicting overnight minimum SP02 before falling asleep

[dfunk]

I use a Viatom/Wellue Sleep-U pulse oximeter at night. Does anyone else notice that they can get a general idea of their overnight SPO2 lower limit by checking SP02 immediately before/after getting into bed, regardless of whether they've got their PAP machine on yet? If my conscious SP02 hovers in the 95%-96% range (with possible momentary dips to 94% or jumps to 97%) as I'm turning in, chances are my overnight minimum is gonna be 90%-91%. If I hold steady in the 97%-98% range while awake/drifting off, I'm more likely to bottom out at 92%-93%, and very rarely 94%. Is this a fluke of inaccurate, inexpensive, consumer-grade hardware? Is my feeling better on days with higher SP02 minimums just placebo? Has anybody else experienced this?