Thread: Best times to LD?

I never really see this subject on DV, and I have rarely seen it discussed.
I think it might be the main reason why some people, me included are having a tough time having an LD, even though we believe we are following the techniques correctly.

When are the best times to have an LD?
Could anyone explain the REM cycle, when it starts to when it finishes, and at what times is it best or possible to enter an LD?

TL;DR When does REM occur in the night, and what times should we set our alarms for?