In the spring the sunrise is getting earlier as time goes by. Then the clock jumps forward an hour, which makes sunrise an hour later, causing the repeat the op talked about.

In the fall, sunrise is getting later. The clock jumps backward an hour, which makes sunrise an hour earlier. This causes the same repeat, in reverse (aka, trending darker rather than lighter).

edit: Also, I have the experience to back this up. I've been one of the living west of my workplace people for too long.