Here's the real annoying question: what happens to our bgs while we are sleeping and not monitoring? If you snack, are you staying high overnight to dip down at fasting and then rise again afterwards (if you skip breakfast)? If you don't snack, are you rising higher while you sleep anyway, or are you curving nicely down until just before waking, and then kicking up as your body transitions into "awake" mode. These are things we Type 2's cannot determine without having CGMs, and they are the things that should determine whether or not we snack before bed (or instead of a snack, have a glass or two of water) and how long we should (or should not) wait after waking before breakfasting.
The other thing is, you didn't mention what your bgs were like before choosing whether or not to have a bedtime snack. If they were already low, then you might be dipping low enough overnight to trigger a larger-scale glycogen release than if you were in "normal" range. If you were high, then either you could be re-triggering insulin release or your body might still be trying to digest your snack and you may get lower-than-expected readings as all the nice, high-fuel blood is focused on your GI tract instead of your fingertips.