Terry, I'm not sure what differences there are between bipolar and Asperger's with the sensory issues. I can only speak from our own experience; basically, it's always seemed to me that the boys have some sort of disordered sensory input. difficult child 1 especially suffered from it in primary school (corresponds with elementary, I think). He found it hard to concentrate with ALL sensory input being distracting. He would mentally fatigue fast, get anxious faster, when there was more sensory input, it really didn't matter too much what sort. For example, trying to listen to his teacher with earthmoving equipment outside the room would be difficult for any kid. For difficult child 1, having lots of different things to look at, a lot of movement or bright colours, was just as 'loud' to him and just as much of a distraction. And, of course, schoolrooms are highly stimulating environments.
A scratchy shirt would also distract him from paying attention; not because he was busy fidgeting, but because it was sensory input which stopped him focussing exclusively on what he had to do.
The teacher he had first would have all the kids sitting around her on the floor and she would sit difficult child 1 right up close, sitting on her feet. He coped best this way.
The following year he had an authoritarian teacher who sat him up the back of the class and got angry with him every time he fidgeted or wasn't paying attention. He crashed & burned in the first few weeks. Of course, he had no diagnosis at this stage because although I had concerns, I kept getting told there was nothing wrong with him.
As he got older he had some support and also learned to cope by narrowing his focus down really tightly, to close out all other distractions. He was on medications for ADHD which also seemed to make it easier for him to concentrate.
Sensory Integration Disorder (SID) affected him in other ways, most notably with toilet training. It's only been in recent years that we've been able to stop reminding him that maybe he's overdue for a long session "in the reading room". He simply didn't get the message from his body, until it was screaming at him.
difficult child 3 - toilet training problems of course, plus food fussiness: he won't eat anything with a creamy texture. He loves coffee (decaf, of course - we won't risk giving him caffeine, ever), but is VERY fussy about the slightest trace of froth on his coffee. He knows that the best coffee has a small amount of natural crema on it but he always tries to spoon it away or drink around it until it settles. We're trying to break him into cappuccino - he knows intellectually that it's frothed milk, not creme, but his preference will always be flat white, I think.
He loves the feel of towelling next to his skin - it calms him down. He only eats a certain variety of a certain brand of packaged frozen fish. The only bolognese sauce he would eat is my recipe, cooked by me. If even husband cooks it, following my recipe, difficult child 3 can tell.
With autism you get stims in a lot of cases. These can be obvious, or subtle. The classic hand-flapping stimulant, where the kid is looking at his fingers and the light through them as he waves his hand, has been described as soothing to the brain, like a cat being stroked. For difficult child 3 we noticed a very early fascination with light flickering through leaves on the trees. He was a week old when we first saw it. At three months we found that the sound of bagpipes, from a piper tuning up (never a pleasant sound) to the massed bands of a parade ground full of pipe bands, would put him to sleep. We tested this over the next few months and it worked without fail. Bagpipes were soothing for him. He also liked other music but was fussy at first. I experimented with different types of music, awake and asleep, and he quickly showed his preferences. With his favourites (always Mozart, some Bach and some Beethoven) he would crawl to the speakers and put his ear right up next to them to feel the vibrations. We couldn't shift him until the music stopped, when he would often cry. It was uncanny - I had a cousin like that, I'd been told. We now think that cousin was an Aspie.
We often find Sensory Integration Disorder (SID) meeting Obsessive Compulsive Disorder (OCD).
easy child 2/difficult child 2 has a fetish for certain textures, especially soft ones, just as she hates anything the slightest bit scratchy in clothing. She won't wear cheesecloth, for example, and only the softest muslin will do. Synthetic satin is OK but some varieties don't breathe, velvet is adored as is furry fabric. She hates wool but wears sheepskin boots (uggs) whenever she can get away with it. She made a fur fabric cover for her school folder, and then carried her folder everywhere - this was a way to acceptably enjoy her obsession in public. She has made cushions and blankets from fur fabric and sleeps with them.
She is also fussy about certain foods, certain noises, everything being lined up just so, and despite the fact that our house is amazingly untidy, our cutlery basket is immaculate. Even the dishwasher has to be loaded with matching forks next to matching forks, etc. A certain amount of this is normal; in our house tantrums are thrown if things aren't right.
For easy child 2/difficult child 2 the bath has to be run at 42.6 degrees C. difficult child 3 likes his bath cooler but is prepared to adapt (we have to take turns in the same bathwater, to conserve the water).
The Sensory Integration Disorder (SID)/Obsessive Compulsive Disorder (OCD) thing - difficult child 3 has been enjoying having my lava lamp nearby while doing schoolwork. The only problem is, he watches it obsessively.
Both boys gave me a classic example here - when our front-loading washing machine arrived and I immediately put a load on to wash, I found the boys in the laundry sitting on the floor, totally engrossed. difficult child 1 said, without looking up, "I don't know why but I find this strangely compelling."
From what I read here, it seems like kids with BiPolar (BP) can be very similar. It is very hard for me to draw a line and say, "This is Sensory Integration Disorder (SID). This bit here is Obsessive Compulsive Disorder (OCD). This bit there is the normal kid, in there somewhere."
We just deal with it and live with it. And keep nesting the cutlery correctly.
Marg