Being autistic means that you have no protection against impulses from outside and inside.
So an autistic child feels best in a structured daily life with as little unexpected events, objects and feelings as possible.

Christmastime is for many autistic children not the happy time it is supposed to be.

At school the regular classes make place for whatever the teacher feels inspired to do.
On the streets there are lights that are only flickering and present a months a year,.... and at home?
The smells are different, there are things added in the room which make it feel unfamiliar and strange, and people feel different.

Dependend on the way autistic children express themselves they show their feelings of being overpowered.

As they have limited ways of perceiving their feelings and thoughts, they have a difficult time dealing with emotions, even the pleasant ones.

So even a child that feels happy and bright by the new surroundings, can express it to the world by having seemingly angry fits with screaming, throwing with things and stamping through the room... for example.

Christmastime is for families with autistic children and children with autistic characteristics a very difficult time.

Especially when there are visitors or if they have to visit other people.
Even beloved grandmothers and -fathers, friends and brothers and sisters feel strange and add to their sense of being lost in an unknown world.

My visits to family and friends always turned out to be a disaster.

At chistmas expectations are high.
People have to behave in a friendly, cooperative, peaceful way.
In our family christmas meant loads of food, lots of talking, and children who had to behave even more than at other times.
I always wondered if the grown ups could remember how they felt as children when they had to behave a 100% in clean clothes. LOL!

When the children got a bit older I tried to limit my visits to the family to a couple of hours, but the result at home was the same.
The visits had disrupted the daily routine. so it took days before they felt a bit well again.

They...
I have one autistic son, one with severe asperger syndrome and one with ADHD, and their father is on the spectrum too.

Even now we don't have family visits anymore, christmastime is a time of longing for a normal family time, with christmasdinner and candles and lots of time relaxing.
Instead it's playing peace-police and all time duty therapist.

If you have people with an autistic or spectrumchild in your family of circle of friends, inform what is good for their family.
They will be surprised, as so many people don't care. Some because they don't know. And some because they don't want to know.

Maybe they ask you to step back, don't expect them at a family gathering.
Well, you can surprise them by delivering their dinner at the door and asking the parents for a day out in january, when the children are to school again.
Maybe they want something for their children you don't approve.

Whatever it is, don't think they're trying to mess up your christmas. They just try to live through christmas in a way that causes as little stress as possible.