I noticed this too. For me, diet was the main culprit in my inconsistency. My armchair theory is that either fluctuating blood sugar levels during sleep or imba

I noticed this too. For me, diet was the main culprit in my inconsistency. My armchair theory is that either fluctuating blood sugar levels during sleep or imbalance of gut microbiome are the cause. A mild ketogenic diet worked wonders for my sleep quality and mental clarity. Intermittent fasting too (on meal a day). Those can be tough to follow, though. I also found that eating no carbs 4 hours before bed and no big meals 2 hours before bed can help as well.