It's easy to imagine sleep deprivation
I don't think it is. My husband never properly got it.
Dd had real real problems from about 6 - 18 months.
She would sleep for 30 mins, scream for an hour. Repeat. Repeat. Repeat. Repeat. Repeat.
My husband did one night of it in that time. (Literally one night - I left him with her at midnight, came back at 7am to take over. He then slept until lunchtime and spent 3 days announcing he was so exhausted. I did the other 364 nights. And generally at 7am I had to get up and crack on with the day. Our marriage hung on solely because telling him to leave would have involved using energy I did not have.)
I hurt. All over. My head, my joints, everywhere. The protective coating that you have in your mouth disappeared so my mouth was full of ulcers. I could only think one step ahead so to get a spoon (3 steps - stand up, open drawer, get spoon) would take me several attempts. I walked across a main road with the pram without looking. I seriously considered doing it again (without the pram) when a car was coming just to get some rest. Ditto swinging upside down on the banisters in the hope they would collapse.
In the middle of all this I went back to my highly paid, highly technical job.
There is over 3 years between my two as it wasn't until Dd was 2and a half that she started sleeping for any amount of time.
She is now 6 and sleeps pretty well! Ds is 3 and has just started sleeping through. For the first time in 6 years sleep is not my biggest obsession.
Wouldn't change them though. Dh was much better with ds (mainly because he desperately wanted a second and promised all sorts when I refused!) so we are still together.