I have often thought that disruptive sleep has a bearing on your well feeling through the day, a good restful undisturbed. (I wish!) sleep does wonders not only only how you feel but on your blood glucose levels.
It doesn't help, when you are going hyper, hypo, hyper, hypo, through the day and night. Fluctuating blood glucose levels do significantly contribute to a restless night, especially when I was in hypo hell, the weird dreams and nightly traumatic sleeplessness, would make me certainly more unwell and with that the diversity in symptoms and whatever follows, the anger, frustration and all the rest and including obviously, tiredness, lethargy, brain fog and forgetfulness!
Since going low carb and not getting the hypos, the rest followed on, sleep would be restful, less dreams, and the well being is back, when I'm tired, it's a good tired.
Sleep is a big huge part of health management and when you get it right, as I have, the benefits are apparent! I still have to use the loo a couple of times a night, but I climb back into bed and fall asleep again.
No more staring at the walls at three in the morning cos you know, even though you're knackered, sleep won't come and the weird dreams are thankfully few and far between!
It's all part and parcel of this condition. Control and not going hyper then hypo is so important!