There's this saying which is oft-quoted in books about babies and sleep, "sleep begets sleep". The idea is that, if your baby gets plenty of daytime sleep then she'll sleep well during the night too, and vice versa.
Yesterday Baby had about four hours of day sleep, twice as much as normal. And last night she woke up for attention SIX TIMES - twice as often as normal. The previous time Baby napped that well, her night was just as wakeful.
I really, really really must stop reading those parenting books.