If you're regularly waking around 3 (as opposed to random times throughout the night) you might want to reconsider cortisol as a possibility, at least as setting a baseline wakefulness that allows you to be easily woken up from a noise. There is a natural cortisol spike at that time, and that combined with elevated levels from background stress causes the same problem for many people who fall asleep without issues, myself included.

The 3am part was just a random picked time. But interesting to know, thanks for sharing! I had some stress related sleeping issues about a year ago, that’s why I started with proactively provoking morning cortisol spikes and preventing them in the evenings which definitely helped. At that time I went through some personal challenges, so it made sense

Second this

Have the same pattern, issue is cortisol/stress, not sounds / etc that happen precisely at night

Built simular things tonwhat Op did (thoug using Oura for sleep tracking, not Garmin)

Result: no statistically significant variations in sounds, CO2 normal etc. Cortisol is what doctors/AI told me first