I've had 5 consecutive nights of getting the new Sleep Stage estimation while wearing a Blaze with the v17.8.401.3 firmware; last night it reverted back to the old sleep-pattern and it doesn't seem to meet any of the 3 specified reasons listed in this article. I slept for more than 3 hours, my battery was half full at the time of syncing this morning, and I actually downloaded the interday heartrate data and there didn't seem to be any major lack of heartrate data. Last night's sleep record was 29,158 elapsed seconds with 12,198 hr recordings and it reverted to the old sleep pattern. The first night sleep stages was calculated was 27,095 elapsed seconds with 11,435 hr recordings.
If I did the math right, that should be 25.32 heartrate recordings per minute yielding the new sleep stages system, and 25.10 heartrate recordings per minute yielding the old sleep pattern system. One difference I did find is last night's sleep log has heartrate recordings as low as 47 bpm at times, but that might actually be relatively accurate as my lowest bpm during a polysomnogram was 48. What am I missing, or is this a bug that Fitbit is trying to fix?
