DS Won't Go to Sleep

I would stop spanking him. I would hold to a routine (book, too!) and if he doesn't go straight to sleep, he can read a book or whatever. We found out that my DD needs a bath, even a short one, to sleep well.

What I would also do is get information on parenting the spirited child. I would work on him as a whole because I bet that bedtime is not the only time he has a fit.

He doesn't have to go to sleep the moment his head hits the pillow, but he needs to be quiet and he needs to stay in bed. What are his reasons for not going to bed? If 8:30 is too late, back it up to 8PM. Find out what time HE needs to start going to bed to get to sleep, even if it's way earlier than you ever expected.

You say it's almost like he wants a spanking - negative behavior is still a means to get attention. So I would find other ways to give him attention - before it gets like that. You have an infant and an older child. Is your middle son getting lost in the shuffle? Sometimes if we give DD attention upfront, she'll behave better in the day.

Stop spanking him for needing your attention. Because that's what you are doing, punishing him for a NEED. He needs to go to bed earlier, he needs you to be calm and not reactionary, he needs to have a bedtime story. He does not need to be hit to be taught to go to sleep.

We were trying to keep our kiddo's naps because our school system still has them lay down until after Christmas...

I feel for you. It seems you're doing okay.

Does he have to share a room with his sibling?
He's a different age now. Then he was then a year ago etc.
I shared a room with my sibling when I was a kid. I HATED it. My sibling made it real unpleasant and I could not sleep with her in the room. Oh and she'd irk me, when my parents did not know nor see it nor hear it.
And if I told them my sibling was irritating me, then she'd make all innocent like she wasn't doing anything. Real frustrating.

He is not getting enough sleep.
He still seems to need to nap.
My son, was a napper... even when he was in Kindergarten.
I didn't stop his naps, when he entered elementary school.
He needed, to nap, still. He'd even tell me.
After school, he'd nap. Even if it was for 1 hour.
And he still went to bed at night, just fine at his regular time.
Which was 8:00pm. And he is 7 now, and his bedtime is still, 8:00pm.

Lack of sleep, actually makes it HARDER, for a child to sleep and to get a good sleep.

And, what does he say... about why he, cannot fall asleep or is not sleeping well?

Spanking him, will NOT work.
It has NOTHING to do, with his sleep problems.
It is the wrong, consequence.
I would, talk WITH him. About it. See, what is happening.
And since he is throwing fits about sleeping, then why is that?
And being over-tired, REALLY makes kids... feel awful. They are not like adults where they can push through it or ignore it. Kids cannot. But they cannot explain that... to the grown up.
TALK with him, in a comforting way and see what is going on.
Because spanking him, is a desperate thing, and has no bearing on sleep or lack of sleep. It just makes a kid upset and not trust, their parent for help.

Your son is young, and still needs a nap.
And/or you need to get him to bed, earlier. Make his bedtime, earlier.
8:00pm.

My middle child had a similar experience. Now, something I've heard recently is really neat. I even use it now that my boys are older. Wish I had it as one of my "tools" when they were little.

I see lots of good advice here. You do need some input from him. Don't wait until bedtime or when he is in the middle of a fit to talk to him. Just make it a part of the day when he feels comfortable enough to talk about it. Ask him to tell you what is going on.

I tried to pay some extra attention to the middle child. I'm the oldest of my siblings and haven't had the experience of being a middle child. I was hoping that I could bolster his confidence in himself most especially by NOT comparing him to his brother.

Well, the "tool" I mentioned above works really well. (I would recommend it after you figure out what is going on at bedtime.) The next day, you say "no, sorry, you don't get your favorite cereal because you got out of bed after bed time" and "no, you can't choose your favorite after-school snack, because you would not stay quiet after bed time." After a while of not being allowed to watch TV or favorite snack or favorite toy, he will connect the two. I think it would help you and your 4yo. Even at the age of 2 or 3 - if the event was in the morning.

Hang in there and don't forget to let us know what "happened next."

What time does he go to bed, and what time does he wake up? Is he going to bed too late, and overtired, or is he going to bed too early, and not tired enough?

My kids were both pretty good sleepers. At that age they went to bed between 9:30 and 10:00pm and slept until 8:00am with no naps, so about 10 hours a day. Our bedtime routine was a snack, then a book, followed by pj's, brushing teeth and bed. We always got out and got some exercise between supper and bedtime too.

He's 4 and you stopped reading him a bedtime story? Did he have issues going to sleep before you stopped the story? Of COURSE you go back to reading him a bedtime story!!!!
I read stories to my kids until my son (eldest) was in about 4th or 5th grade! The youngest was in at least first if not 2nd grade (they are 3 years apart). So youngest was 6 or 7 and eldest was 9 or 10 years old. You've already stopped and he's not even 5 yet? Why did you stop?

ETA:
Ok, sorry. Now that I have stepped back for a moment, and focused a bit more on your last paragraph, here's what I think:
He is going to bed too late. At 4, he would probably do better with an earlier bedtime... like around 7:00 or 7:30. He doesn't have to go to bed at the exact same time as the older sibling, or as early as the younger sibling. By the way... how old IS the older sibling? It may be that your middle child is missing some quiet time at bedtime that he really needed to settle down for the night. Just because he isn't a "baby" or a "toddler" anymore doesn't mean that he can put himself to sleep like an older child. They still very much enjoy and often NEED that quiet time before bed with some attention from mom or dad. A tent is fun, but not comforting like snuggling with a storybook for 15 minutes with Mom. Talking to him and warning him isn't comforting in the same way either, particularly if it is laced with correction about how he needs to go to sleep.
He may in fact be pushing you until he gets a spanking. Not purposefully to gain the spanking, but to get SOME reaction from you that draws out strong emotions. I bet after the spanking he cries himself to sleep, exhausted from the entire ordeal.

He's ONLY 4. And when he does turn 5, he'll ONLY be 5. He's not grown. He probably seems really mature and old next to your youngest these days. But 4, 5 (and yes, even 6) is still very young. Read stories to him and snuggle with him for as long as you can. Depending on how old the older sibling is, HE may even enjoy story time as well.
You can read chapter books with him.
There is a reason it is a staple amongst parents' routines for bedtime across generations.