Just started my night qual and instructor said (IIRC) that night flight (UK at least) is considered IFR so above the transition level,the quad rule must be obeyed.With all the recent high pressure (1035Mb the other night),this can have a significant effect on the first available FL.
I can forsee that this could bring problems with respect to Class A and going into IMC (cloud

).......
Will clarify that on next lesson.
MM