OP
. Parenting is tough.
Firstly I'd like to say that I was fairly AP with DS, not that I knew that's what it was at the time. I just went by what felt right and what worked, and if something didn't work, I tried something else.
But my parenting style with DD is very different because she's a very different baby. For her if I don't put her down alone when she's tired and sing a little lullaby (which makes her drop to sleep in approx 2mins), then she screams blue murder and arches away, basically fights as much as she can. She's been like that since a few days old. I initially parented her the same as DS, but it didn't work for her. She is an incredibly happy and smiley baby, who loves cuddles and attention when awake but not to go to sleep.
My point is I totally changed how I settled a baby to sleep because although cuddles was the only was for DS, it was completely wrong for DD. They are born with some of their characteristics.
Whatever your doing to settle your DS at the moment, isn't working for him. He is waking every time he enters the light sleep fase of the sleep cycle, instead of going back into a deeper sleep. Do you honestly think that's good for him? It's really not. You need to start trying different methods. There are lots of methods in between fully AP and CIO. It's about finding what works for your DS.
Also please don't be taken in by people who claim studys show short periods of crying cause the same as severe neglect. The only studies have shown that children whose basic needs aren't met (being fed, changed, generally played with and cared for) and are just left in isolation and ignored all the time are harmed. Those studies relate to neglect. A child in a loving home, who is fed, changed, played with and cared for but is occasionally left for very short periods of time to cry when all basic needs have been met are in no way related to the studies. It is a completely different thing.
Also remember that it is only 2or so generations ago when babies basic needs were met, then they were left in their pram until the next feed 4hours later. It was the norm. This is stricter/harsher than would be done now yet there wasnt a complete generation showing the same characteristics as severely neglected children, was there?
So Google, look for different methods and then come up with your own methods to try. Just don't listen to people comparing serious neglect to a couple of mins crying.
He maybe too old now but my own version of pickup/putdown helped DS.