Try adding another "constant". aka something that doesn't change when you get up.
With you in the bed he feels the bed, temperature, & you. He hears you breathing, & him breathing. As soon as you get up though the bed moves, the temperature cools, & you're gone. Yikes!!! Sounds like he's supersensitive. What really hit me was "within minutes" comment. If he doesn't wake up when the bed moves, it looks like he does once the other things being absent are noted...like the sheets cool.
What worked for us (and what eventually trained my son from being a super-light sleeper to a baby/kid who can sleep through a marching band was 3 things:
- His Blankie
- Music at night
- Giving up on being quiet.
The last one was the most important for us. <Laughing> Actually, to this day he's still really suspicious if we try to leave "sneaky-like"...but he had this honed to a science as a baby/young child. However, if we just got up (not carefully, other then not to squish him), walked out & shut the door and went about normal activities (talking, laughing, washing dishes, watching a movie, practicing the guitar, etc.)after the first few nights of him waking up and us putting him back down he slept like a log through everything. We even started to have friends over at night.
The music we played was NPR's jazz/blues station and we just left that on quietly. I'm sure any kind of music would work.
His blankie is something we fostered a dependence of...but it's a great tool, especially for sleep & traveling (of which we do a lot....travel that is...sleep we could use more I'm sure!!!) He's six now, and has been gradually weaning away from it for the past few years. But it was one of those constants. Besides, my personal opinion is that it can in no way hurt a child to have them love MORE. Mum, Da, brothers, sisters, family, pets, blankets, the world around them....to me it's all the same. The more they love the better. I DO know that many people don't feel that way, I actually have a friend who's afraid to give her little one things they can hug and carry around with them because it might mean that she would love Mum less. I mean really! :) Eh. Her own insecurities. How could anyone love their mum less?
In any event, those were what worked for us. I'm sure whatever your choices are will be best for you!!
With hopes for laying in the arms of Morpheus!!
Z.