On my note about waking up too early after only 4-5 hours, today someone helped me make a connection and rec: I had increased the amount of time between my last meal and sleep, typically 6pm and 11pm, in order to improve sleep, but a possible consequence of that might be an overnight drop in blood glucose. What worked for him is casein protein powder at night - it's a slower digesting protein so it lasts longer overnight, and it contains tryptophan.
I tried some tonight and will share an update!