The Day No One Woke Up, by Polly Ho-Yen

This is another excellent, creepy novel by the author of Boy in the Tower. Ana feigns sickness to get out of going to school, where she's being bullied by Tio - her next-door neighbour and one-time best friend. Another friend, Layla, tries to intercede and only makes things more awful. Then Ana's aunt is suddenly taken ill, suffering from a weird, unsettling loss of memory. And then everyone starts getting sleepy...

As with Boy in the Tower, this is John Wyndham for kids. We start in grounded reality and very relatable problems, and then the weirdness slowly creeps in, ever more unsettling. That means the more outlandish, sci-fi bits of the plot feel solid and real; they are earned. Without spoiling the central wheeze, it's a fun reversal - things being done to humans that humans to do others. 

The conclusion satisfying ties up all the mysteries but leaves a couple of questions - what might the children remember of all they've been through, and what is the fate of the character-I-won't-spoil they encounter? A brilliant book, one that linger longer in the memory...