This is possibly the worst advice and the worst thing to do but when Chloe was 7mths she would have two very long sleeps during the day then start up until about 1 or 2am then want to get up at 6am it just got too tiring and it ment I couldn't go out during the day so one day instead of letting her go to sleep during the morning I took her out to the playground then a kids music group then to visit friends the whole time I acted was enigectic and exciting to keep her awake and as happy as possible she only had 1 sleep from 12 til 3. I eventually took her home and put her to bed at 7pm she grizzled for a long time then went to sleep, I gave her a dream feed at 10ish before I went to bed then she slept until 7am. from then on this stayed her routine she is now 2and a half and does pretty much the same thing.
It's a bit mean to them I guess but if it means a happier mum then it's worth it.