High sleeping SpO2, but EOV spikes

[n8vz]

• I’m experiencing an anomaly recently.  I had low B12 levels, so my doctor had me start taking sublingual B12 supplements once a week.  My nighttime SpO2 levels within just a few days rose from nightly averages of 90 to 95, to 95 to 100.  My lows now are where my highs used to be.  The graph is very dramatic.  The anomaly is this: I’m now getting more nights, where I have EOV graph spikes.  If my SpO2 averages are markedly higher and the range on a given night is small and considerably above 90, how can I have EOV spikes showing high variation.  Something is not right here. 
  
  Here’s last night’s graphs, the SpO2 range was 94 to 98. The upturn in the SpO2 graph coincides exactly with when I began the B12 supplementation.

[n8vz]

P.S.  The night before the above graphs, I had my first ever 90 (Excellent) sleep score.  I’ve had Fitbit devices now for more than 5 years.  I’m usually somewhere I’m the 80s, with an occasional lower score.

[RiekoC]

Hello @n8vz 

You might find this page helpful in understanding how Fitbit tracks Estimated Oxygen Variation (<-- click link) as well as the factors that impact this stat. Although you have high SpO2, your EOV could have spikes due to a breathing disturbance, like loud snoring. 

[n8vz]

Thanks for the link.  So, it appears that if your SpO2 goes rapidly from something like 99 to 92, you get an EOV spike on the graph, even though that’s not technically a clinically significant desaturation.  Not very useful.