Z.A.
I'm pulling an infrequent one for me and not even reading the other responses...Because i actually feel really strongly about this one.
-Babies know what they need.
-Children know what they want.
-Adults have agendas.
Object permanence is a psychological concept that breaks down into English as "having just figured out that something may go away and NEVER COME BACK". Wee bit scary, isn't it?
Personally, when my 5 year old read something about fire-safety and made the cognitive leap "Omigod, what if my mum and dad died in a fire and I was all Aloooooooon?????" I didn't shove him away, and tell him that he needed to learn to deal with these things on his own, because he was interrupting mummy. I pulled him onto my lap and rocked him, and hugged him, and comforted him until he wasn't afraid anymore. I know few people who would shove their crying child away and tell them, sorry, figure it out on your own...I'm obviously not burnt alive. Yet for some reason, over the past 30 years it's become really popular to do that with infants. I don't get it.
This phase doesn't tend to last long. Usually a few weeks at most. You'll know it's coming to a close when just a few pats on the bum soothe him back to sleep. One trick is to start something that continues all night long (something permanent & therefore comforting). We played jazz/blues...I know other parents who use a moving starlight projection, or a fan, or even one family i know of who used a "lonely puppy" toy...the kind designed for puppies that has a heartbeat and simulated breathing.... the theme tends to be something that has movement, whether it visual, auditory, or physical.
Another trick, for getting more sleep, if you can wing it... is for one partner to go to bed early/get up early with the baby so the other partner can go to bed late / sleep late after being up with the baby. We couldn't do this (I just stayed up late and got up early :P), but I've done it for my SIL for a week so she could sleep until noon and catch up on some needed zzzzz's. It tends to work the best for people who need large blocks of sleep in order to feel rested. Obviously, some people are wired for napping. I don't know about you, but i am unfortunately not one of them. For ME it's better to be running on 3-4 hours of sleep, for a week, and then crash for 12 hours... then to add a nap. Regardless of what the studies show.
Doing montessori style parenting you will run up against a LOT of parents telling you the myriad reason why x,y,z won't work and why you have to have strict schedule, and how to make your child conform to your schedule. However, montessori-style parenting is the kind of parenting that has been around for millenia... not until the 1950's do you run into "everything must be seperate, sterile, and DO NOT BOTHER ME, you're not on my SCHEDULE, you're not allowed to be hungry/scared/etc until 2 HOURS FROM NOW" style parenting :P <laughing> can you tell I'm a bit persnickety and or biased? Totally biased. At least, I know it takes all kinds.
Enough about me. I think you're doing fantastic, and have good instincts. You've ruled out medical problems and you're looking for a solution that will work for your family. Go with your gut. Give whatever you choose time to work, but if it doesn't, try something new. Improvise, adapt, and overcome it what it's all about. And before you turn around twice, it's gone, in a blink. I swear I was sitting in my rocking chair nursing my son while reading a book and listening to nina simone @ 3am DIEING for sleep, maybe a couple of months ago...but it was seven years. Even though you're tired, these moments are so precious. They're literally gone in a blink.
With love,
Z.