I also looked at the sleep study, and was struck by a few things when reviewing your posted PSG.
(1) the REM flutter at 05:30 thru 06:10 with wakes in between.
(2) the N3 Stage sleep happened only once, and after a brief REM sleep at about 04:05. Generally, N3 sleep comes first and immediately followed by REM. Your note about the slow wave sleep (deep sleep) being disrupted is interesting, the way I see it, the slow wave sleep was one continuous 14 minutes from about 04:35 to 05:00.
(3) Also, it is noted that the PLMS are all in a cluster before deep sleep and REM, and there is alot of fluttery Wake Sleep Wake stuff throughout that cluster. The jerking or motion did not increase your heart rate like I would expect if stress or distress were associated with the movements. Also, mostly it did not wake or even arouse you.
(4) All those pulse changes really strike me as heightened stress levels, though maybe not respiratory related distress. Anytime the pulse rate increased 15 bps (to 70 or above from 55 bps) or (to 65 or above from 50 bps) there was a distress that caused it.
you can see on the linked image how sleep stages typically get distributed throughout the night:
https://els-jbs-prod-cdn.jbs.elsevierhea...0a/gr3.jpg
And, notice that most jumpy O2 Sats are generally during sleep in supine position (on back).
QAL