I've experienced symptoms like you describe, an almost overwhelming bias toward hypos. Sometimes I can explain these episodes as delayed hypos after a day of sustained exercise. But sometimes there just appears to be no rational reason for this incessant dive in BGs.
As much as we PWDs like to be consistent with our treatment using the same insulin sensitivity factor (ISF) and insulin to carb ratio (I:C), I think that sometimes our bodies' metabolic needs can temporarily change. I also think that those changes can occasionally be extreme.
I can't guess what happened to you but I have a theory. While our metabolisms generally like to be consistent sometimes they act more like the exception than the rule. Perhaps the liver, which usually secretes a consistent amount of glucose (it also varies according to time of day), may decide to stop putting out its usual glucose flow for a few or even several hours. If my speculation is correct, then the "usual" insulin that we deliver, basal and bolus, will overwhelm the small amount of available glucose and drive us low.
I have an insulin sensitivity factor of 1:50. That is, if I take a correction dose of one unit of insulin, I can usually expect it to subtract 50 points from my current BG. I've read that some PWD here use different ISF's for different times of day. ISF variability within one day doesn't seem that odd to me. What if your ISF can change a lot, like going form 1:50 to 1:100, just every once in a while?
One thing I know for certain is that diabetes and blood glucose management is a dynamic game. We all depend on using the same I:C and ISF because they usually work. Diabetes, however, seems to delight in changing the rules, sometimes drastically. That's why it's essential that we monitor closely and respond appropriately when the rules drastically change.
You may never figure out what metabolically happened last night but I congratulate you for rolling with the punches and giving your body just what it needed when it needed it!
Now you need to remain watchful that perhaps your I:C and ISF may have changed as part of a trend, and last night was just a harbinger of that new trend.