usual "going to sleep whenever I feel so exhausted that I know I'll be able to fall asleep instantly".

That's how I tend to sleep either :( I fight against myself to make me sleep before 5 am as I need to wake up before late afternoon for photography, and generally I know falling asleep after 6-7 am hits hard my health.

I advise you to put up curtains on your windows that provide 100% darkness while you are sleeping - even slight light destroys melatonin, the sleep hormone, and that makes your sleep shorter and less restorative. Actually you can consume melatonin in pills when your circadian rhythm destroyed (but don't ruin your natural ability by pill abuse). "Another cool thing: higher level of melatonin may cause more colorful dreams. Kids have highest melatonin level and the best quality of sleeping and night dreams. :)

Ask Claude :D