These brain chemical rewards apparently do not work on me, my (still young) kids provide no such rejuvenation. Luckily I'm a deep sleeper so I have no sleep deprivation problems.
This may change with age. My children were cute but didn't engage me much emotionally while they were still mostly crying, pooping, and trying their best to hurt themselves. Once they became more multi-faceted that changed.
For all the difficulties, children are rejuvenating and fun and provide purpose to life.