Yes, poor sleep can make a big difference.
I have discovered (by various self experiments wearing a Libre) that my Blood glucose rises until I eat. If that breakfast contains carbs (eg yog and berries) then my bg just keeps climbing. However, if my breakfast is protein and fat, not carbs, then my bg stops rising and drops to its normal (non DP) levels.
further experiments showed that a few cashews, or an oz of cheese, is sufficient to stop my bg rising between waking and breakfasting. Or lunching, if I am skipping brekkie.
of course, your body may respond differently.