I'd say if his mom isn't concerned, his dad has a right to do something about it. If his dad decides he needs to go see the doctor, he should let mom know that's what he's doing. If you are the one that actually takes him, I don't think it's a big deal as long as it's with dad's authority and mom is informed (and dad should give mom an opportunity to take him first) but if she doesn't, then as long as you aren't even going to make her pay any of it, then dad can take him or have you take him.

A couple of things:

- First off, I commend you for being alert and concerned. That doesn't sound right, and IMO, your instincts are on target as far as this indicating a possible medical problem. To help things along, keep a diary for a week or two of SS's eating, playing and sleeping habits. When he gets up, what he eats for breakfast, lunch, dinner and snacks. What he did in the afternoon as far as play. Nap times, bed time. Lots of Drs. don't really hear "He sleeps all the time!" but will pay attention to a written log - it's objective and quantified.

- Secondly, I'd advise treading very carefully here. (And even more so if you're right than if you're wrong.) This does need to be initiated by DAD, not by StepMom, even if you're really the one behind the scenes pushing all the way (which I'd urge you to do). While BioMom might be both distracted and laid-back, having YOU take her son to the doctor for something this "gray zone" could easily be interpreted as you considering her "neglectful", which could start WWIII with some women.

As far as how to handle the issue with BioMom, that'll vary with the dynamics of each family, but I'd definitely try to stay on "her side" if that's at all possible.

You need to let the boy's father handle this. He is not your child and there is not a lot you can do. unless he gets seriously ill and no one is doing anything about it, then I would step in then. Could she be drugging him? I had a grandson that slept a lot of the day and found the young mother was giving him 3 different cold medicines and they all had the same meds in them. She was unknowingly over dosing him.

So far I agree with your concerns and the replies.
Here's my opinion, for what it is worth.*
Does your SS crave sugar or is he just given too much? This may be a self-medicating diabetic/hypoglycemic/anemic. Does SS eat odd things like dirt, paint, a lot of ice?
It could also be any number of medical issues; some doctors are concerned when a parent starts self-diagnosing their kids, so whoever accompanies your SS should explain the Sx and let the Dr recommend tests and treatments and offer HIS suspicions. This avoids the appearance of the overly anxious parent. Now, if the Dr does nothing but pat you on the head and say the child is just active, and refuses to delve deeper, find a new Dr. Be calm, but firm.
Make sure you keep the journal previously mentioned but be careful not to micro-analyze every little thing you think might support your theory.

*Not a MedPro, just someone who is luckily surviving the medical merry-go-round...

I appreciate all of the great advice. I am going to try the journal, but that will be difficult because we split time with him 50/50 and that is alternating days and weekends. We do have him for a week of vacation coming up soon, but he'll be exhausted that week anyways since we plan on staying on the beach all day. We've already gone through the bedwetting thing with his mother and that ended up working out ok in the end, but she will probably think I'm some crackpot hippie because I do read nutrition books and try to learn more about our bodies.

About the sugar, I don't think he really craves it. From the time he has eaten solid foods, he has always been given a "treat" after dinner. Don't get me started on that. I don't think any child should be "rewarded" for eating their meal. However, he'll pick one of those nasty popsicles (in the plastic bag/packaging) over homemade cakes or cookies. Crazy... I guess you could say his tastebuds aren't really developed yet. :)

I know she's not neglectful and she definitely doesn't give him medicine on a regular basis. We don't either. It just seems like she's not very quick to react if he gets sick, like she knows best and he can pop a kids Tylenol and he'll be ok. She just seems a bit clueless.

I meant to ask: do you have BC? Perhaps SS just hasn't outgrown the need for a nap. School can be tiring.
One thing I thought of after I reread your OP was sleep disturbance. If your SS is sleeping poorly, it doesn't matter how many hours he is in bed.
Cavities may or may not have anything to do with his diet. My DH has perfect teeth at 43yrs and MIL always spoiled her kids with sweets, and continues to do so with GC. I also never had a cavity until I was 25, and I was a poor eater as a kid. Pop is the bigger culprit these days. Acid erodes the enamel and sugar feeds the bacteria. A lot of adults choose processed over homemade, so it may be a matter of liking the familiar. MIL never serves dinner without dessert, and DH jokes, "Life is short, eat dessert first." (No, we don't.)I tried not to make sweets a reward, nor did I make them taboo. I never really made food a big issue with my kids. They like homemade and store-bought junk, I prefer homemade- It tastes better!
I also tend to play down illnesses and avoid too many meds or emergency dr visits with my kids. We seem to be a nation of worriers and quick fix fanatics. Most illnesses are viral, and build our immune system. Tylenol/Motrin for a fever is sufficient. Overreacting to every cough or sniffle is more common than people realize.

"It just seems like she's not very quick to react if he gets sick, like she knows best and he can pop a kids Tylenol and he'll be ok. "

I'm not very quick to go to the doctor when my kids get ordinary little virus-type symptoms either. If one of my otherwise healthy boys aren't getting visibly better by the end of Day #2, then I'll evaluate calling the Doctor on the morning of Day #3. Or of course, if something just doesn't seem 'right' I'll call much sooner.

Anyway - just keep the journal for the day's he's with you and don't worry about the rest of the time. And don't wait until the week at the beach because, as you've already noted, that'll be an exhausting week anyway.

And Mrsmaddog's advice about pre-interpreting the symptoms and 'pat-on-the-head' doctors is right on target. It seems the automatic response of many pediatricians is to reassure first, ask questions later...