I’m not surprised that there should be differences between the two watches. There have been plenty of hardware revisions between them.
May I suggest?
Have a word with your primary care doctor. Not urgently; you can wait until your next annual physical — but don’t forget about it, either.
Waking multiple times but having no recollection of waking is fairly common. It can have any number of causes, but it’s a classic symptom of sleep apnea, which is one of (if not the most) common sleep disorders. Basically, the muscles in your neck relax to the point that they don’t hold your airway open, and you start to suffocate. Naturally, your body briefly goes into panic mode, you wake up, catch your breath … and, there no longer being anything to panic about, you go right back to sleep.
There are, of course, lots of other possible causes for you to wake and not remember; just ask any sleepwalker or anybody who lives with one.
So … a word with a doctor would be a good idea. Somebody who has a clue would know what sorts of questions to ask (and, if appropriate, what sorts of other diagnostics to perform) to make sure that nothing serious is going on. (There’s almost certainly nothing serious going on.) And the doctor would be able to tell you what to be aware of for the future, and might have some suggestions for things to do now.
For example, assuming it’s sleep apnea, there are simple exercises to build up the neck muscles; if you’re carrying a few extra pounds, this would be a good reason to try to slim down; and, if it starts to interfere with your waking hours (such as if you’re perpetually tired even after ostensibly getting a full night’s sleep), there are devices (such as a CPAP machine) that are called for. (But, if it’s something else entirely … well, that’s for the doctor to figure out.)
Again: not urgent; put it on your list, but just make sure it doesn’t perpetually fall off the list. Sleep is one of the pillars of health; making sure you sleep well will pay dividends your whole life.
b&