It's because he's only nearly 4wks old, isn't it?
In a given 24hr period he might sleep all night except a feed in the middle, go in his basket no problem, sleep between feeds during the day and generally be pleasant to live with.
Then in another 24hr period he'll spend the best part of 10 hours awake, cluster feed furiously until it's just comfort-sucking and I'm on the verge of weeping, fall into a deep slumber in my arms then wake within minutes of going into the basket, whinge/moan/insist on feeding then not really bother sucking, fall asleep again, refuse to sleep in basket, whinge/moan/insist on feeding, fall asleep again etc etc ad nauseum until 2am when I want to cry/shout at him/ask why at not even 4 weeks of age he wants to put me through such endless frustration and tedium after demonstrating that he's perfectly capable of sleeping BUT JUST DOESN'T WANT TO!
What if I WANT TO SLEEP? If I can't sleep I'll go mad/explode/die and then he won't be able to feed but he doesn't seem to give a toss about this logical outcome should he persist in being so damn frustrating.
It's making me really dislike him sometimes, which is awful because he's only tiny and he isn't trying to drive me to the brink of insanity. But just because he isn't specifically trying doesn't mean he isn't succeeding. Please tell me this will all cease at the magical 6wk mark and he will miraculously develop a failsafe in-bed, will-sleep mechanism? I think I might jump out the window if he doesn't.