The thing with seratonin levels is that seratonin is measured after the infant has passed away. I don't believe the Japanese and other south-east Asian countries that don't have SIDS are just genetically blessed, because seratonin is related to stress, or the absence of it. These other cultures have co-sleeping as the norm and don't have a culture of baby-separation that we have (cots, prams, glorified bouncinettes, outsourced childcare etc) - these aren't genetic factors, they are cultural ones.
I have no idea what this book says about it, and I hope it does explore these things - I'd read it if it did! Because the discourse about SIDS in this country is like a dog chasing its tail, especially since the new research findings came out - i.e. what can we give to babies to boost their seratonin levels/screening for low levels/'finally there is a physiological reason for it'.
I'm not saying that SIDS is caused by parents, I'm saying that lowered seratonin is a characteristic of our children here in Oz because of how maternal nurses etc say we should do things WRT sleeping.
Research has also shown that co-sleeping babies have their breathing regulated by the CO2 from the mother's breathing - it seems to trigger the brain's centre for taking a breath when an infant goes a while without taking a breath in. You can't get that when you're not sleeping near your child.
Our culture places a lot of importance on parental independence of children, disguised as training babies to be independent, and a lot of women dont' want to deal with the comments and judgments if friends etc find out they co-sleep, so they don't. Let's face it, the running commentary when you DO follow the prevailing parenting trends is bad enough, let alone when you do things 'differently', so I can understand when parents just go with the 'conventional wisdom'.
I think the only way to avoid lowered seratonin levels is to practice parenting that enhances physical closeness to baby - baby-wearing, co-sleeping, breastfeeding (shown to enhance emotional wellbeing via the 'feel-good' receptors in the brain being stimulated by neural pathways around the lips during sucking on a breast in various research papers I came across a few years ago) - and not by injections of it (if there is such a thing).
As I said, I don't know the contents of the book the OP is talking about. I CAN recommend, for a read on the physical benefits of a tactile relationship with baby, the book by Sharon Heller called "The Vital Touch", which talks about the psychosocial and biological effects of various types of 'touching' for babies and mothers. SIDS is a topic in there, too
I just feel that talking about this kind of parenting is taboo when discussing SIDS, as talking about breastfeeding seems to be taboo to expectant mothers because of the 'softly softly' approach that benefits no-one.
Also, if Australian health authorities started advocating more tactile parenting, there'd be a lot of baby-product companies crying foul - it's a huge industry when you think about it. Separated parenting is our norm, and it's not working for us
Two cents worth.
I would very much like a precis on the contents of this book - as SB said, if it's important it needs to be freely disseminated!