sazzle snap again 
. Ds is generally very content, kicks happily around on the floor if fed and not tired, almost never has crying-in-pain episodes. He naps well, poos every 3-5 days and, despite spitting up after nearly every feed, is not in any pain and does not require medication for reflux. He even manages a 5 hr stretch most nights.
However, he has stork marks and I had eczema as a toddler which cleared up overnight when my mum switched me to from cow's to soya milk. Plus I've eaten very little dairy since very early on, so he could possibly have mild cmpi and just not be showing any symptoms other than not sleeping 6+ hours at night. He also has a seemingly permanently blocked nose - can that be linked to cmpi? It certainly seems to irritate him at night.
So would he sleep 8 hours if I cut every trace of dairy from my diet? Unanswerable question to my mind. If it took 5 weeks to make a difference, then either he might be sleeping better by then anyway, or might be in the middle of the 4 month regression.
If it only affected me I would try anyway, but cutting out Indian takeaways and refusing to eat lunch out would affect dh, too, and his job is exhausting and stressful enough without me taking away life's little pleasures.