I don't understand how people say they "get used to it". Maybe if you are getting 3 hours a night or even 4 it is just about survivable.
I lived off 45 minutes three times a night for six months. My DD just did not sleep for the first six months. Woke very hour or two for a feed. Each feed took an hour to get the milk down her and settle her, by the time she dropped off it was almost time for her to wake up again. She never napped in the day and could stay awake for 10 hours straight.
It was the worst six months of my life.
I felt ill. My body ached. Eyes itched. Vision was blurred. I would walk the streets pushing the pram (desperately hoping the baby would sleep) and often not feel safe to cross the roads, my brain just couldn't function. I would also stare at other mothers with babies wondering "are they getting any sleep?" If not, how are they managing it? Why doesn't anyone tell you how awful it is?
I spent hours googling "how to get baby to sleep/why won't my baby sleep." I used a sleep consultant. A cranial osteopath. Read every book going. Did dark room, good bedtime routine, white noise. Nothing fucking worked. I wanted to die. I was obsessed with sleep. DH took over at weekends and I used to literally collapse and sleep for 13 hours. I fantasised about that night all week.
The photos of me back then, without make up, are horrific. I look like a smack head. Alive but dead at the same time. No amount of coffee helped.
I was hugely resentful of people with babies who slept. A friend had twins who slept for five hour stretches from birth. She hit the jackpot! Now when she has an odd night without sleep she's all over Facebook complaining about it. I laugh hollowly. She doesn't know she's born!
At six months DD suddenly slept from the dream feed at 10 pm until 5 am. Best day of my life. Suddenly the world was in colour again.
I will never have another child as I cannot risk going through that again. People who do it for years? I salute you. It would kill me. Six months of it very nearly finished me off.