@Arletta @eonity @actuallyautistic Same, I sleep on about a 25.1 hour cycle.
After a decade of considering it an AuDHD quirk I started looking into it more a few days ago and found r/n24 on reddit and this stupidly huge document by a neuro researcher who has the condition and claims personal success with several hours of very bright morning light: https://circadiaware.github.io/VLiDACMel-entrainment-therapy-non24/SleepNon24VLiDACMel.html
No guarantee it would help you personally, but at least it's serious research and not "grandma said this helps with sleep".
@stephenczetty @squipo @Arletta@mas.to @eonity @actuallyautistic
If that worked for you, you can also get an alarm clock that will slowly turn on a bright light to wake you up. I tried one and found that it just made me roll over, so I wasn't facing the light, and took it a step further - wired all the lights in my bedroom to turn on (No escape! Mwahahaha!) and it's made a huge difference for me.